Today's Veterinary Practice, July 2017

IN THIS ISSUE 32 CUTANEOUS BIOPSY 42 GASTRIC DILATATION AND VOLVULUS 64 ABDOMINAL ULTRASONOGRAPHY: LYMPH NODES

Anaphylactic Shock Effective Diagnosis and Treatment

JULY/AUGUST 2017 VOLUME 7, NUMBER 4

Don’t let your client’s best friend get sick.

Introducing the Nobivac® Canine Flu Bivalent vaccine • Protection against Canine Influenza Virus (CIV) H3N2 and H3N8 in one vaccine1 • 2-in-1 coverage offers safe, up-to-date protection1 • Monovalent CIV H3N2 and CIV H3N8 vaccines are also available

When to vaccinate • Vaccinate puppies from 7 weeks of age with 2 doses administered 2 to 4 weeks apart • Annual revaccination with 1 dose is recommended

Reasons to vaccinate • Keep pet parents happy by sparing their pets from annoying cough attacks • Protect dogs under your care and in the community from highly contagious CIV • Prevent outbreaks in your practice and boarding facility Nobivac® Canine Flu Bivalent - Convenient CIV H3N2 and H3N8 Protection in one dose

DON’T WAIT, VACCINATE WWW.DOGINFLUENZA.COM Ask your Merck Animal Health representative for details!

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Reference: 1. Nobivac Canine Flu Bivalent [product label].

Madison, NJ: Merck Animal Health.

Essential protection for essential bonds Copyright © 2016 Intervet Inc., d/b/a Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved. US/NCI/0816/0047

JULY/AUGUST 2017

VOLUME 7, NUMBER 4

An Official journal of the

An official journal of the NAVC, Today’s Veterinary Practice is the trusted source for peer-reviewed clinical information in small animal veterinary medicine. Our goal is to enhance knowledge and encourage confidence, inspiring the highest quality of veterinary care. As an NAVC publication, our audience has access to world-class continuing professional development developed for the global veterinary health care community.

Subscriptions (only): 630.739.0900, CDS/Today’s Veterinary Practice 440 Quadrangle Drive, Suite E, Bolingbrook, IL 60440. Email subscription form to subscriptions@CDS1976.com or fax to 630.739.9700 Free subscriptions only to qualifying subscribers.* For a new subscription, confirmation, or renewal, please visit tvpjournal.com to fill out an online form. For updates, please include your subscription ID from label. To have a form emailed or faxed to you, please contact us at our 800 number or email above and provide email or fax number.

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Eastern States Veterinary Association, Inc (NAVC) reserves the right to determine eligibility for a free subscription.

WARRANTIES, LIMITATIONS. Except as expressly set forth herein, Eastern States Veterinary Association, Inc (NAVC) makes no warranties whatsoever, express, implied, or statutory. NAVC specifically disclaims any implied warranty of merchantability or fitness for a particular purpose. In no event will NAVC be liable to you or any third party for any indirect, punitive, special, incidental, or consequential damages (including loss of profits, use, data, or other economic advantage), however it arises, even if NAVC has previously been advised of the possibility of such damage. All rights reserved. No part of this publication may be reproduced in any form without written permission from the publisher. Entire contents ©2017 Eastern States Veterinary Association, Inc (NAVC).

Editor in Chief Simon R. Platt, BVM&S, MRCVS, DACVIM (Neurology), DECVN University of Georgia College of Veterinary Medicine SRPlatt@NAVC.com

Chief Executive Officer, NAVC Thomas M. Bohn, MBA, CAE TBohn@NAVC.com

Laura C.S. Walker Senior Vice President of Sales and Publishing LWalker@NAVC.com Chris Kelly, Group Publisher CKelly@NAVC.com Rick Boggess, Vice President of Sales and Marketing, NAVC Publishing RBoggess@NAVC.com Nick Paolo, MS, MBA, Director of Operations and Finance, NAVC Publishing NPaolo@NAVC.com Robin Henry, Executive Editor RHenry@NAVC.com Jackie D’Antonio, Managing Editor JDantonio@NAVC.com

Editorial Advisory Board P. Jane Armstrong, DVM, MS, MBA, DACVIM, (Small Animal Internal Medicine) University of Minnesota, College of Veterinary Medicine

Renee Luttrell, Director of Sales RLuttrell@NAVC.com, 610.558.1819 Sondra Reynolds, Director of Audience Development SReynolds@NAVC.com Michelle Taylor, Senior Art Director David Beagin, Art Director Julie Butler, Assistant Editor Megan Cox, Staff Writer

Mark Cofone, VMD, DACVS Veterinary Specialty Center, Wilmington, Delaware

Cheryl Hobbs, Staff Editor Suzanne B. Meyers, Staff Editor Lisa Wirth, VMD, Staff Editor

NAVC Board of Directors Sheila Grosdidier, RVT, PHR Veterinary Management Consultation Evergreen, Colorado

President Gail Gibson, VMD Immediate Past President Melinda D. Merck, DVM President-Elect K. Leann Kuebelbeck, DVM, DACVS

Garret Pachtinger, VMD, DACVECC Veterinary Specialty & Emergency Center Levittown, Pennsylvania

Vice President Cheryl Good, DVM

Michael Schaer, DVM, DACVIM, DACVECC University of Florida College of Veterinary Medicine

Harold Davis, Jr, BA, RVT, VTS (Emergency & Critical Care) (Anesthesia & Analgesia)

Treasurer Laurel Kaddatz, DVM Directors Paige Allen, MS, RVT

Sally Haddock, DVM Bob Lester, DVM

FEATURES

52 RACE-APPROVED CE CREDIT ARTICLE

Anaphylactic Shock: How to Effectively Diagnose and Treat Jennifer L. Lyons, MS, and Jordan R. Scherk, DVM, DACVECC This article provides an overview of anaphylaxis; the pathophysiology of its mechanism of action, including mediators and shock organs; and treatment recommendations for a variety of clinical signs associated with anaphylactic shock.

42

FEATURE

Gastric Dilatation and Volvulus: Stabilization and Surgery Desiree Rosselli, DVM, DACVS (Small Animal) Gastric dilatation and volvulus is characterized by abnormal twisting of the stomach on its mesenteric axis, with subsequent gastric gas accumulation and distention. This article discusses the diagnosis and treatment of this acute, life-threatening disorder.

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6 8 13 4

ADVERTISER INDEX TODAY’S VETERINARY NEWS INSIDE NAVC ERRATA

Today’s Veterinary Practice does not, by publication of ads, express endorsement or verify the accuracy and effectiveness of the products and claims contained therein. The publisher, Eastern States Veterinary Association, Inc (NAVC), disclaims any liability for any damages resulting from the use of any product advertised herein and suggests that readers fully investigate the products and claims prior to purchasing. The opinions stated in this publication are those of the respective authors and do not necessarily represent the opinions of the NAVC nor its Editorial Advisory Board. NAVC does not guarantee nor make any other representation that the material contained in articles herein is valid, reliable, or accurate; nor does the NAVC assume any responsibility for injury or death arising from any use, or misuse, of same. There is no implication that the material published herein represents the best or only procedure for a particular condition. It is the responsibility of the reader to verify the accuracy and applicability of any information presented and to adapt as new data becomes publicly available.

Today’s Veterinary Practice (ISSN 2162-3872 print and ISSN 2162-3929 online) is published bi-monthly (Jan/Feb, Mar/Apr, May/June, Jul/Aug, Sept/Oct, Nov/Dec; 6x per year) by North American Veterinary Conference, NAVC, 622 East Washington St, Ste 300, Orlando, FL 32801. Periodicals postage paid at Orlando, FL 32801 and additional mailing offices. Application to Mail at Periodicals Postage Prices is Pending at Glen Mills, PA 19342 and additional mailing offices. POSTMASTER: Send all UAA to CFS (See DMM 507.1.5.2); NON-POSTAL AND MILITARY FACILITIES: send address corrections to CDS/Today’s Veterinary Practice, 440 Quadrangle Drive, Ste E, Bolingbrook, IL 60440.

2

TABLE OF CONTENTS

To read this issue online, visit tvpjournal.com

DECHRA’S IV FLUID PORTFOLIO

Reliable Solutions to Suit Your Hospital’s Needs Vetivex® Lactated Ringer’s Solution Injection, USP 500 and 1000 mL bags

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For current promotion pricing on select fluids or to order, please contact your Dechra or distributor representative or call (866) 683-0660.

More Information at www.dechra-us.com 24-hour Veterinary Technical Support available (866) 933-2472.

Non-urgent Technical Support available via email at support@dechra.com.

CAUTION: Federal law restricts these drugs to use by or on the order of a licensed veterinarian.

Dechra is a registered trademark of Dechra Pharmaceuticals PLC. Vetivex is a registered trademark of Dechra Limited.

COLUMNS

7 EDITOR’S NOTE

Paying for Moments of Certainty?

Simon R. Platt, BVM&S, MRCVS, DACVIM (Neurology), DECVN

20

VET REPORT VITALS

36

What Does a Rise in Antimicrobial Resistance Mean?

Molly McAllister, DVM, MPH

24

The Flea-Infested Pet: How to Manage the Pet and Its Environment Cherie M. Pucheu-Haston, DVM, PhD, DACVD

AHS HEARTWORM HOTLINE

Turning Up the Heat on Heartworm Diagnosis

64

Brian A. DiGangi, DVM, MS, DABVP

32

PRACTICAL PARASITOLOGY

IMAGING ESSENTIALS

Ultrasonography of Peritoneal and Retroperitoneal Spaces and Abdominal Lymph Nodes Clifford R. Berry, DVM, DACVR; Elizabeth Huyhn, DVM; and Danielle Mauragis, CVT

DERMATOLOGY DETAILS

Dermatology Diagnostics: Cutaneous Biopsy Sarah Bartlett, DVM, MS, DACVD

70

CLINICAL INSIGHTS

What to Do With Lumps and Bumps Sue Ettinger, DVM, DACVIM (Oncology)

74

ASPCA PRACTICAL TOXICOLOGY

Ethanol Toxicosis: A Review Tina Wismer, DVM, DABVT, DABT

Errata

Atkins CE. Heartworm disease: the science, the practice, the future. Today’s Veterinary Practice 2017;7(1):87-92.

The author regrets that an error appeared in the dosage of ivermectin used in a microfilaria suppression test on page 90.

The dosage should be 50 mcg/kg, not 50 mg/kg.

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TABLE OF CONTENTS

Pucheu-Haston CM. The flea-infested pet: overview of current products. Today’s Veterinary Practice 2017;7(3):90-95.

The time until topical fluralaner is expected to be very water resistant was misstated on page 93 to be 3 hours. The correct time is 3 days.

To read this issue online, visit tvpjournal.com

The infl ammation Tamer Help get your patients moving again with Duralactin®.

When an active pet becomes less mobile, whether from injury or normal aging, owners trust you to do all you can to get their dogs and cats moving again.

While many supplements can strengthen cartilage and connective tissue, only Duralactin® products contain MicroLactin®, to help support joint health and reduce inflammation throughout the body with minimal side effects.

Here’s why Duralactin products should be a key part of your treatment of inflammation and joint conditions.

• Ideal for long-term use and high-risk pets • Easy once-a-day dosage • Palatable, with a variety of flavors and dosage types • Multiple formulations for canines and felines • Proven with 14+ years of clinical use SATISFACTION GUARANTEED

DURALACTIN® products come with a risk-free, 100% money-back guarantee if you or your client are not 100% satisfied with results.

To find out more about how Duralactin tames inflammation, speak to your sales representative, or visit our website at duralactin.com.

This product has not been approved by the FDA nor is it intended to diagnose, treat, cure, or prevent any disease. Should only be used through consultation of a veterinarian and in conjunction with an overall wellness program.

Microlactin is a registered trademark of Stolle Milk Biologics, Inc. Duralactin is a registered trademark of PRN Pharmacal, Inc. ©2017 PRN Pharmacal, Inc. All rights reserved.

800-874.9764

UniversityPRN.com

CE as needed, when needed.

ADVERTISER INDEX

Ansell Healthcare | ansell.com Powder-free Surgical Gloves . . . . . . . . . . . . . . . . . . . . . . . . 41

Caution Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian.

Before using this product, please consult the product insert, a summary of which follows: Indications INTERCEPTOR PLUS is indicated for the prevention of heartworm disease caused by Dirofilaria immitis; and for the treatment and control of adult roundworm (Toxocara canis, Toxascaris leonina), adult hookworm (Ancylostoma caninum), adult whipworm (Trichuris vulpis), and adult tapeworm (Taenia pisiformis, Echinococcus multilocularis and Echinococcus granulosus) infections in dogs and puppies two pounds of body weight or greater and six weeks of age and older.

Dosage and Administration INTERCEPTOR PLUS should be administered orally, once every month, at the minimum dosage of 0.23 mg/lb (0.5 mg/kg) milbemycin oxime, and 2.28 mg/lb (5 mg/kg) praziquantel. For heartworm prevention, give once monthly for at least 6 months after exposure to mosquitoes (see EFFECTIVENESS).

See product insert for complete dosing and administration information.

Contraindications There are no known contraindications to the use of INTERCEPTOR PLUS. Warnings Not for use in humans. Keep this and all drugs out of the reach of children.

Precautions Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention (see EFFECTIVENESS).

Prior to administration of INTERCEPTOR PLUS, dogs should be tested for existing heartworm infections. At the discretion of the veterinarian, infected dogs should be treated to remove adult heartworms.

INTERCEPTOR PLUS is not effective against adult D. immitis.

Mild, transient hypersensitivity reactions, such as labored breathing, vomiting, hypersalivation, and lethargy, have been noted in some dogs treated with milbemycin oxime carrying a high number of circulating microfilariae. These reactions are presumably caused by release of protein from dead or dying microfilariae.

Do not use in puppies less than six weeks of age.

Do not use in dogs or puppies less than two pounds of body weight.

The safety of INTERCEPTOR PLUS has not been evaluated in dogs used for breeding or in lactating females. Studies have been performed with milbemycin oxime alone.

Adverse Reactions The following adverse reactions have been reported in dogs after administration of milbemycin oxime or praziquantel: vomiting, diarrhea, depression/lethargy, ataxia, anorexia, convulsions, weakness, and salivation.

To report suspected adverse drug events, contact Elanco US Inc. at 1-888-545-5973 or the FDA at 1-888-FDA-VETS. For technical assistance call Elacno US Inc. at 1-888-545-5973.

Information for Owner or Person Treating Animal: Echinococcus multilocularis and Echinococcus granulosus are tapeworms found in wild canids and domestic dogs. E. multilocularis and E. granulosus can infect humans and cause serious disease (alveolar hydatid disease and hydatid disease, respectively). Owners of dogs living in areas where E. multilocularis or E. granulosus are endemic should be instructed on how to minimize their risk of exposure to these parasites, as well as their dog’s risk of exposure. Although INTERCEPTOR PLUS was 100% effective in laboratory studies in dogs against E. multilocularis and E. granulosus, no studies have been conducted to show that the use of this product will decrease the incidence of alveolar hydatid disease or hydatid disease in humans. Because the prepatent period for E. multilocularis may be as short as 26 days, dogs treated at the labeled monthly intervals may become reinfected and shed eggs between treatments.

Effectiveness Heartworm Prevention: In a well-controlled laboratory study, INTERCEPTOR PLUS was 100% effective against induced heartworm infections when administered once monthly for 6 consecutive months. In well-controlled laboratory studies, neither one dose nor two consecutive doses of INTERCEPTOR PLUS provided 100% effectiveness against induced heartworm infections.

Intestinal Nematodes and Cestodes Treatment and Control: Elimination of the adult stage of hookworm (Ancylostoma caninum), roundworm (Toxocara canis, Toxascaris leonina), whipworm (Trichuris vulpis) and tapeworm (Echinococcus multilocularis, Echinococcus granulosus, Taenia pisiformis) infections in dogs was demonstrated in well-controlled laboratory studies.

Palatability In a field study of 115 dogs offered INTERCEPTOR PLUS, 108 dogs (94.0%) accepted the product when offered from the hand as if a treat, 1 dog (0.9%) accepted it from the bowl with food, 2 dogs (1.7%) accepted it when it was placed in the dog’s mouth, and 4 dogs (3.5%) refused it.

Storage Information Store at room temperature, between 59° and 77°F (15-25°C).

How Supplied INTERCEPTOR PLUS is available in four strengths, formulated according to the weight of the dog. Each strength is available in color-coded packages of six chewable tablets each. The tablets containing 2.3 mg milbemycin oxime/22.8 mg praziquantel or 5.75 mg milbemycin oxime/57 mg praziquantel are also available in color coded packages of one chewable tablet each.

Manufactured for: Elanco US Inc. Greenfield, IN 46140, USA Product of Japan NADA #141-338, Approved by FDA Elanco, Interceptor and the diagonal bar are trademarks owned or licensed by Eli Lilly and Company, its subsidiaries or affiliates.

PA100437AMX_BrS1

Advanced Veterinary Ultrasound | avuetulsa.com Ultrasonography Equipment . . . . . . . . . . . . . . . . . . . . . . . 69

Antech Diagnostics | antechdiagnostics.com Lab diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Bayer Healthcare | bayerdvm.com Supplements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Dechra | dechra-us.com IV fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Elanco | elanco.com Interceptor Plus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 8, 9 Duramune Lyme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Ultra Vaccines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35 Bronchi-Shield Oral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 Masterfoods USA | royalcanin.com Royal Canin feline diets . . . . . . . . . . . . . . . . . . . . . . . . . . . 10, 11 Merck Animal Health | doginfluenza.com Nobivac . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . inside front cover Merial | frontline.com Frontline Gold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . back cover Midmark | midmarkanimalhealth.com Midmark products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 National Veterinary Associates | nvaonline.com National Veterinary Associates . . . . . . . . . . . . . . . . . . 18, 19 NAVC | navc.com VMX 2018 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Nestlé Purina | purinaproplanvets.com NeuroCare diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Nutramax | solliquin.com Solliquin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . inside back cover Pet Health Pharmacy | pethealthpharmacy.com Compounding services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 PNC Bank | pnc.com Financial Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 PRN Pharmacal | prnpharmacal.com Duralactin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Protégé Biomedical | clotitvet.com ClotIt Vet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Ultimed Inc | ulticare.com iPet Pro . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 VetFolio | vetfolio.com VetFolio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

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TABLE 6OF CONTENTS

AD INDEX

Simon R. Platt, BVM&S, MRCVS, DACVIM (Neurology), DECVN University of Georgia

EDITOR’S NOTE

EDITOR’S NOTE

Paying for Moments of Certainty?

As the debate around human healthcare insurance currently dominates our lives in the United States, it’s worth asking relevant questions about insurance options for the pets we treat. As veterinary care continues to advance, so do the associated costs, which undoubtedly impact “best possible care” options. Pets are legally considered to be the property of their owners, so pet insurance is similar to car or homeowner’s insurance. It falls under the Property and Casualty classification and functions as indemnity insurance, which means it operates very differently than the human managed-care model we are all familiar with. However, it has been reported that an inhibiting factor to the growth of pet health insurance (PHI) in the United States is a prevailing fear among veterinarians that widespread use will result in a managed-care system. Are we really on that path?

The first pet insurance policy was written in 1890 by Claes Virgin, who was the founder of Länsförsäkrings Alliance, and was initially focused on just horses and livestock. In 1947, the first pet insurance policy was sold in the United Kingdom, a country second only to Sweden in its level of pet insurance coverage (approximately 23%). In the United States, only approximately 0.7% of pets are covered according to the US Department of Clinical Veterinary Science and the Pet Food Institute. However, a recent survey by the Associated Press found that 41% of US pet owners are extremely or somewhat worried that they could not afford the medical bills for a sick pet.

Why should there be such a drastic difference in the level of PHI coverage between countries, especially when you consider that the concept of purchasing healthcare insurance is much less culturally accepted in Europe than it is in America? Is there a simple, explicable difference between the mindset of a pet owner in the two regions when it comes to healthcare? Few places provide answers.

In 2007, the North American Pet Health Insurance Association (NAPHIA) was created as a reputable, centralized organization to represent the interests of PHI companies in the United States and Canada,

and advocate for the collective PHI industry.

In 2016, NAPHIA undertook a comprehensive research initiative focusing on both pet owners and veterinarians and their beliefs and activities around PHI. This report can be downloaded in full from the website naphia.org/veterinary-professionals.

Although there is a broad awareness of PHI among the veterinary community based on this survey, there is still a high level of uncertainty regarding the details of the products available, which creates a hesitancy to discuss PHI with our clients. There is also a significant portion of veterinarians who don’t recommend PHI based on perceived economic or time burdens. Furthermore, more than 40% of veterinarians questioned believed that it makes no difference to them whether clients have a PHI product or not. Remarkably, only 5% of respondents believed that PHI companies will have too much influence in the veterinary profession if it becomes commonplace.

So what is it that’s really stopping us from embracing a degree of financial certainty when it comes to the payment for the services we provide as a profession?

For a considerable period of time, the AVMA has endorsed the concept of PHI. It recognizes that viable PHI programs will be important to the veterinary profession’s ability to continue to provide high-quality services. Of course, guidelines should be in place to ensure that individual programs work in the best interests of our profession and our clients. Such guidelines have been published by the AVMA and include the requirement of a veterinarian/client/patient relationship, never interfering with the veterinarian’s fee structures, and being transparent about how the terms and conditions of their plans will impact coverage and costs.

It is obvious that the benefits of PHI can only be determined by individual owners and their circumstances. However, despite existing doubts about the overall financial benefits of PHI policies, there is certainty that at some point in their life, most pets will need medical care, and that the good care we provide is not free.

JULY/AUGUST 2017

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TVPJOURNAL.COM

7

TODAY’S VETERINARY NEWS

BI DECLARES 2017 THE YEAR OF THE SMALL DOG Boehringer Ingelheim (BI), maker of METACAM (meloxicam), has announced a campaign to raise awareness that small-breed dogs are as at risk for osteoarthritis (OA) as larger dogs. BI will provide veterinary practices with educational materials to help their teams learn more and to prompt conversations about OA in small dogs with their clients. Canine OA is often associated with larger breeds because of the well-known challenges bigger dogs often face with joint function and discomfort. However, small-breed dogs can also suffer from joint disease for a variety of reasons, including obesity, luxating patellas, trauma, Legg-Calvé-Perthes disease, or normal wear and tear causing cartilage damage.

NEW Mosquito Control Guidelines The Companion Animal Parasite Council (CAPC) has issued its first-ever set of guidelines on mosquito control.

The guidelines recommend an “Integrated Pest Management (IPM)” strategy, which employs the use of EPA-registered repellents/insecticides on pet and humans, minimizing exposure and altering the environment to discourage mosquito growth development. The guidelines emphasize that repelling and killing the vector should be a part of the strategy to protect ink relief. canines, and several products are available for use Thon dogs to repel and kill mosquitos for an entire month, including some that are labeled to control other ectoparasites as well.

InsId e

■F or more information about the campaign and METACAM, visit metacam.com.

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in appetite • Vomiting known tis, also• Change in bowel movements, such as diarrhea or ase in behavior, • Change dise black, tarry,

rthri A decade ago, few teoa drugs available to treat =oswere pets in pain. Today, joint veterinarian-pr ative escribed NSAIDs offer deg pets, helping control as relief toener symptoms such as, inflammation, swelling, stiffness and joint pain. In addition to providing pain control, veterinarians also believe that NSAIDs help pets heal better and faster. ful

OA Effectsandofpain swollen, mobility to loss of

Consistent, open communication with your veterinaria n and close monitoring of your pet can make NSAIDs a beneficial and costeffective treatment option.

What should you do before your pet uses NSAIDs?

Ask your veterinarian about the benefits, risks

of any medication, e. and side effects An including informed pet is not alonowner is theNSAIDs. best defense Your dog OA. against serious side effects from NSAIDs. s has

lt dog 1 in 5 adu Tell your veterinarian about your

The American Animal Hospital Association is an international organization of 6,000 companion animal veterinary care teams, comprised of more than 36,000 veterinary professionals. Established in 1933, AAHA is the only organization that accredits veterinary practices throughout the U.S. and Canada for dedication to high standards than 3,000 AAHA-accreditedof veterinary care. More practices pass regular reviews of AAHA’s stringent accreditation process that AM. patient care, client METACcovers service and medical protocols.

For pet care information or referral to an AAHA tice, visit www.healthypet.co pracm. ©2007 by the American Animal Hospital Association. rights reserved.

All

pet’s symptoms and current medications, including prescriptions, over-the-counter drugs, vitamins, herbal supplements and flea control products.

Giving NSAIDs in combination with any other medications/ supplements could seriously harm your pet.

All pets should receive thorough history and physical examinations, as well as appropriate blood and urine testing, before initiation of NSAID therapy. Ask your veterinarian about the testing protocols that are best for your pet.

For more information

12599

watch for while

or bloody stools such as activity levels, aggression or lack • Seizures of coordination • Yellowing of gums, skin or whites of the eyes (jaundice) • Change in drinking d, habits — frequency or amount consumed ame • Change in urination habits =infl — frequency, color • Change in skin or smell — redness, scabs or s leading scratching joint • Lethargy and/or depression More serious side effects include gastrointestina cases, kidney and l bleeding, ulcers, perforations, and in liver damage, and death. rare

from the FDA, visit

What should you do while your pet is using NSAIDs?

Drugs used to control pain in pets, such as NSAIDs, should be given only when necessary and in the smallest effective dose. If your pet’s condition seems to improve, you should discuss continued use of NSAIDs with your veterinarian.

Never give NSAIDs to a pet or increase the dose or frequency without your veterinarian’s instructions.

Because each pet responds to NSAIDs differently, no one medication is considered more effective or safe than another.

Blood and urine testing should be performed on a regular basis during the use of NSAIDs.

Campaign materials include downloadable dog owner booklets and pain medication guides.

Watch for any NSAIDs side effects in your pet. If you suspect an adverse reaction, stop the use of the drug and contact your veterinarian immediately.

http://www.fda.gov/fdac/features/2

006/506_nsaid.html

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Heartgard is a registered trademark of Merial.

, Elanco and the Diagonal Bar are trademarks owned or licensed by Eli Lilly and Company, its subsidiaries or affiliates.

TODAY’S VETERINARY NEWS 8Interceptor © 2017 Eli Lilly and Company, its subsidiaries or affiliates. USCACINP00189 ®

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AFSCAN ANNOUNCES 2017 RESEARCH AND STUDENTSHIP AWARDS The African Small Companion Animal Network (AFSCAN) has announced the recipients of the 2017 AFSCAN Research and Studentship Awards. The awards, now in their second year, aim to promote small animal clinical research relevant to the African continent and to facilitate the training and development of veterinary students and academics working in Africa.

The AFSCAN Research Awards offer academics working at a veterinary school in Africa the opportunity to secure a grant to fund a locally relevant clinical research project of their devising and to be partnered with a research laboratory overseas. These 2 projects have been selected for funding: • Dr. Hezron Nonga from the College of Veterinary and Medical Sciences, Sokoine University of Agriculture in Morogoro, Tanzania, has received funding for a 2-year project titled “Safeguarding Public Health through Control of Zoonotic Parasites of Dogs.” This award is being supported by Zoetis and the Petplan Charitable Trust.

• Dr. Olusegun A. Fagbohun from the University of Ibadan, Nigeria, has received funding for a 2-year project titled “Molecular Epidemiology of Rabies Virus in Dogs in Nigeria.” This award is being supported by the Swiss Association for Small Animal Medicine.

TODAY’S VETERINARY NEWS

The AFSCAN Studentship Awards enable an African undergraduate veterinary student to spend 6 to 8 weeks participating in a research project related to disease or the welfare of companion animals of relevance to African society.

These 3 awards have been made this year: • Veterinary student Esther Ombura from the University of Nairobi, Kenya, will be working on a project titled “Antimicrobial Resistance in Dogs.”

• Veterinary student Victor Ishengoma from the Sokoine University of Agriculture, Tanzania, will be working on a project titled “Canine Transmissible Venereal Tumour in Tanzania: People’s Awareness and Disease Occurrence in Selected Villages in Morogoro.”

• Veterinary student Lois Sanni from the Federal University of Agriculture, Ogun State, Nigeria, will be working on a project titled “Evaluation of Lipid Peroxidation and Plasma Antioxidant in Arthritic and Non-arthritic Dogs.”

■L earn more at wsava.org/article/ driving-veterinary-learning-africa2017-research-and-studentshipawards-announced-afscan.

Got news? Submit your press release for consideration for inclusion in Today’s Veterinary News at editor@NAVC.com.

Chosen submissions will be edited before publication.

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IMPORTANT SAFETY INFORMATION

Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention.

Prior to administration of Interceptor Plus, dogs should be tested for existing heartworm infections. The safety of Interceptor Plus has not been evaluated in dogs used for breeding or in lactating females. The following adverse reactions have been reported in dogs after administration of milbemycin oxime or praziquantel: vomiting, diarrhea, depression/lethargy, ataxia, anorexia, convulsions, weakness, and salivation. Please see full product information on page 6. *Heartgard Plus hookworm species: Ancylostoma caninum, Uncinaria stenocephala, Ancylostoma braziliense.

JULY/JUNE **(Taenia pisiformis, Echinococcus multilocularis and Echinococcus granulosus).

2017

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TODAY’S VETERINARY NEWS

NEW HEARTWORM INCIDENCE SURVEY The American Heart Society (AHS) has announced its latest survey data, along with unveiling a new heartworm incidence map based on data from veterinary practices and shelters across the country. Numbers reported by participants in the 2016 AHS Incidence Survey indicate that the average number of positive cases per veterinary clinic has been inching upward. The average number of dogs diagnosed per clinic in 2016 rose by 21.7 percent over 2013 numbers.

The AHS revealed the top 5 states in heartworm incidence were Mississippi, Louisiana, Arkansas, Texas, and Tennessee—all states that have been in the top tier since the AHS began tracking incidence data in 2001. Rounding out the top 10 states were South Carolina, Georgia, North Carolina, Alabama, and Florida.

■Y ou can learn more at heartwormsociety.org, and an online treatment app is available at heartwormtoolkit.com.

LATEST ON WSAVA KETAMINE CAMPAIGN The World Small Animal Veterinary Association (WSAVA) has stated that “ketamine is an essential medicine” and that it has particular value for spay and castration initiatives. Last year, WSAVA began a campaign after learning about efforts by some countries to put the drug under international scheduling, which could put access to it at risk in many parts of the world.

WSAVA’s campaign to promote the importance of ketamine included an online petition signed by more than 14,000 individuals (primarily veterinarians) from around the world. Thanks to those efforts, the accessibility of ketamine is not likely to be discussed by the UN Commission on Narcotic Drugs during 2017.

■T o learn more and view the infographic highlighting the importance of ketamine, visit wsava.org/article/wsava-ketamine-campaign-–-update.

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TODAY’S VETERINARY NEWS

TODAY’S VETERINARY NEWS

First-Ever Airport Veterinary Hospital Opens at JFK On June 8, history was made at JFK when Compassion-First Pet Hospitals opened AirHeart Pet Hospital at New York’s iconic airport. The hospital is located inside the ARK at JFK, “the world’s first privately owned, 24-hour animal terminal and airport quarantine center.” AirHeart Pet Hospital’s mission is to provide crucial medical care for animals making their way through and living around JFK.

pets and other live animals being transported annually in the U.S., veterinary medical care is critically needed. We strongly believe this will be a model to carry forward to other airports across the country and perhaps across the globe.”

Lauren Jordon, DVM of AirHeart, added, “Because of our location, we will face some of the most interesting medical challenges, so we have ensured our stateof-the-art facility and the professional staff are fully equipped to meet any issue that comes our way.”

As you may have guessed, “AirHeart” is inspired by groundbreaking aviator Amelia Earhart. The hospital hopes to pay homage to the historic figure by becoming a pioneer in its own work, as the first “distinctly branded, ground-up hospital with the sole purpose to serve...veterinary medical needs in an airport setting.”

AirHeart cut no costs in its efforts to provide firstclass veterinary care to JFK patrons. The hospital is fully staffed with 5 veterinarians, 13 licensed veterinary technicians, and 13 veterinary assistants.

The facility in which they work is state-of-the-art, including 6 exam rooms, two isolation wards, two operating rooms, a treatment room, a radiology suite, a special procedures suite, a pharmacy, and a lab area.

John Payne, CEO of Compassion-First Pet Hospitals, confirmed his belief in this purposedriven project, saying, “With more than two million

Initially, AirHeart will be open Monday through Saturday 8:00 am to 6:00 pm, with hours expected to be extended beginning on July 31st to 8:00 am to midnight Monday through Saturday and on Sundays from 8:00 am to 6:00 pm.

■ For more information, visit airheartpets.com.

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TODAY’S VETERINARY NEWS

INSIDE NAVC

Mia Cary, DVM NAVC Chief Collaboration Officer, Veterinary Innovation Council Executive Director

Aaron Massecar, PhD Veterinary Innovation Council Telehealth Project Manager

INSIDE NAVC

Veterinary Telehealth: What Is It, Where Are We, and What’s Next?

Attend a conference, pick up a trade publication, or simply talk with other veterinarians and one word keeps coming up again and again: telehealth. The term is as misunderstood as it is polarizing. It promises to open up new markets by catering to millennials and threatens to displace the veterinarian’s place at the center of care.

industry stakeholders to develop success models and best practices that will be shared with the profession. The VIC seeks to delineate between cases for which telehealth is appropriate and those for which it is not. We are pairing clinics with telehealth providers and learning where and when telehealth tools are most effectively used.

An issue that causes so much concern and presents so many opportunities calls for an industry-wide, collaborative approach. In January 2016, the Veterinary Innovation Council (VIC) was formed to tackle the largest challenges and opportunities facing the profession. Spearheaded by the NAVC, the VIC includes stakeholders from across veterinary healthcare (navc.com/veterinary-innovationcouncil/our-team/). Its first mission is to make sense of telehealth so that veterinarians can sidestep its impediments and capitalize on its benefits.

So far, we have learned that:

The VIC has been working with telehealth providers (Box 1), veterinarians, state boards, pet owners, and

WHAT IS TELEHEALTH?

• The term telehealth is ambiguous.

• Many veterinarians, companies, and pet owners already use telehealth.

• Appropriate uses for telehealth include pre-existing business models.

• There are easy ways to begin using telehealth tools.

• Telehealth can be used without violating the veterinary–client/patient relationship (VCPR).

To start with, a few definitions may be useful: • Telehealth: The overarching term that encompasses all uses of technology geared to remotely deliver health information, education, or care.

BOX 1. Veterinary Telehealth Providers • Activ4Pets: activ4pets.com • Fetcha.Vet: fetcha.vet • PetDesk: petdesk.com • Petzam: petzam.com • Televet: gettelevet.com • VitusVet: vitusvet.com • WhiskerDocs: whiskerdocs.com

• Telemedicine: A subcategory of telehealth that is a tool, or use of a tool, to augment the practice of veterinary medicine (eg, using Skype or an app to communicate with a client and visualize the patient for a postoperative follow-up examination and discussion).

• Teleconsulting: A subcategory of telehealth that occurs when a general practice veterinarian uses telehealth tools to communicate with a veterinary specialist to gain insights and advice on the care of a patient.

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INSIDE NAVC

HOW IS TELEHEALTH BEING USED?

Three models are effective:

Professional Use of Telehealth

• No-charge first exam • Often results in need for in-person visit (anecdotally, people who connect through telehealth first tend to visit 50% more and sooner and spend 20% more in person)

If you’re texting a client to see how Fluffy is doing or answering a question about medication side effects, you’re using telemedicine. If you’re monitoring an animal remotely, even if it is in the clinic and you are watching vital signs from another computer, you’re using telemedicine.

Clients often want more advice than Dr. Google can give, but don’t have the time or finances to see a veterinarian, so they use telehealth providers to answer questions through text or online services.

Because the providers are aware of the VCPR legislation, most neither prescribe nor diagnose online. We have all heard of companies or veterinarians who use secret forums, like those found on Facebook, to diagnose and prescribe.

VIC condemns the use of telehealth tools when it is inappropriate and violates state legislation. We favor promoting the judicious use of these tools to extend more healthcare to more animals. Examples are emails, texts, instant messages, phone calls, sending of photos and videos, and live videos.

Appropriate Use of Telehealth Tools The telehealth scenarios that we see most frequently and those with the greatest success are the following: • Postoperative follow-up • Dermatologic concerns • Behavioral issues/training • Transportation issues • Hospice care • Basic triage (whether the pet should be seen by the veterinarian) • Environmental concerns/hazards that might contribute to a particular condition • Long-term care monitoring For these scenarios, telehealth tools provide sufficient information to assist pet owners without the necessity of a hands-on physical examination. In some cases, the tools are insufficient and an in-person exam is required; in those instances, veterinarians are discounting the in-person visit according to the cost already paid for the telehealth service.

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INSIDE NAVC

• Additional feature of a pre-existing wellness package • No charge (or charge included in package) • Convenience for client • Per-usage charge • By-the-minute or usage charge • If in-person exam still required, costs credited to client’s account Getting Started The most effective way of getting started with telehealth is to follow the “lean startup” method: Start with 1 or 2 low-risk cases and 1 or 2 doctors and clients. Learn what is successful and measure the outcomes. Slowly expand to include another doctor, another client, and another use case. Then measure and repeat. An example of this is using a text service to inform clients of negative fecal results. Slowly add more use cases and clients until you can diagnose and prescribe within the confines of your state legislation.

Using Telehealth Within State Legislation All states except Connecticut (as well as the District of Columbia) forbid diagnosis and prescription without a valid VCPR that is established through an in-person exam. As was found in human healthcare, this legislation might be challenged in court because of its antitrust properties. Whether company- or client-driven, there are many examples of legislation crumbling under consumer pressure. A protectionist strategy of reinforcing legislation that goes against client demands is never a good approach. Veterinarians who are gaining an understanding of and comfort level with telehealth will be in a better position to use telehealth tools appropriately as pet owner demand increases.

Veterinarians must be allowed to exercise their best judgment regarding when telehealth tools should be used and when they should not. If the veterinarian does not feel that sufficient information can be gathered through remote, electronic means, then those tools should not be used. However, if veterinarians can gather enough information from remote digital tools, then they should use these tools as long as doing so is in the animal’s best interest. The VIC, the American Veterinary Medicine

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Association (AVMA), the American Association of Veterinary State Boards, and the Veterinary Medical Association Executives are just a few of the organizations working collaboratively to address these concerns.

Pet Owner Use of Telehealth In March 2017, the VIC conducted a telehealth survey of pet owners in the United States to better understand their perceptions and uses of telehealth tools. A total of 678 pet owners completed the 5-question survey; while the survey does not represent all pet owners, the results do give a sense of pet owners’ attitudes. The charts show the results of the survey (Figure 1).

Unsurprisingly, most respondents have not used telehealth tools. What is surprising are the reasons for the lack of use. Roughly one-third of respondents said that they didn’t know that telehealth tools existed. When that number is combined with the 26.4% who said that the tools are not available to

Overall, the responses are clearly mixed. This could be because the market for telehealth tools is still nascent; the tools are being developed and awareness is growing, but they are not yet in widespread adoption. Our preliminary results show an appetite for telehealth tools, and that appetite is satisfied when pet owners are aware of where and when to use the tools.

The pet owner survey will be conducted again in March 2018, and those results will be shared with the profession.

WHAT’S NEXT FOR VETERINARY TELEHEALTH? We have not only learned that veterinary telehealth is coming but how it is coming. Telehealth tools reduce client wait times while increasing veterinarian revenue, all while operating within the confines of the VCPR.

QUESTION 1. Have you used a telehealth tool (eg, text, video consult via tablet or smartphone) to communicate remotely with a veterinary healthcare provider about your pet?

QUESTION 2. If yes, what telehealth tool did you use? (Note: When respondents filled in the specific “other” category, most replied, “I don’t use telehealth tools” or a similar statement.)

QUESTION 4. If you have not used a telehealth tool to communicate with a veterinary healthcare provider about your pet, how likely are you to do so in the future?

QUESTION 5. Why or why not?

FIGURE 1. VIC telehealth survey of pet owners.

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them, more than 50% of pet owner respondents are not taking advantage of telehealth tools.

INSIDE NAVC

QUESTION 3. Would you recommend to a friend that they use telehealth tools to communicate remotely with a veterinary healthcare provider about their pet?

INSIDE NAVC

The future presents 2 main opportunities for veterinary healthcare: (1) further clarifying legislation and implementation and (2) incorporating new technologies.

Many open questions about telehealth remain, from informed consent and liability issues to revenue models and practice workflows. These issues are being clarified by lawyers and state boards from a legal perspective and by veterinarians, telehealth providers, and pet owners from a practical perspective. For example, earlier this year the University of California, Davis, released an update1 on how their telemedicine services save time and money and help improve air quality. Practitioners of human pediatrics2 have addressed patients’ inability to speak, and we would be wise to learn from their experience.

telehealth pilots. Please email your perspectives on challenges and opportunities facing our profession to VIC@NAVC.com. For information on the VIC Veterinary Innovation Awards, see Box 2.

Telehealth has primarily focused on communication tools.

Incorporation of new technologies will only continue, from connected litterboxes and implantables to wearable devices3 and in-home diagnostics. We are moving from an era of once- or twice-a-year visits to an inexpensive and constant stream of 24/7 360° data that will provide deeper insights into our pets’ health. Veterinarians must be at the center of animal care, but this will happen only if they adapt to and incorporate these new technologies.

By working together as a profession, we can create solutions and best practices that bring us into the future of veterinary healthcare, a future that emphasizes a personalized, customized, patient-centered approach.

4. North American Veterinary Community. Interested in telehealth? navc. informz.net/informzdataservice/onlineversion/ind/bWFpbGluZ2luc3R hbmNlaWQ9NjM2NDA1OCZzdWJzY3JpYmVyaWQ9MTA2NTg2Mzk4 OQ==. Accessed April 2017.

For more information, read the comprehensive AVMA telemedicine report, along with the VIC Board of Directors consensus response.4 While telehealth is the current VIC focus, we are considering future projects to run in parallel with the

References 1.

Casey C. Telemedicine saves patients time, money. University of California. March 21, 2017. universityofcalifornia.edu/news/ telemedicine-saves-patients-time-money?utm_ content=bufferb60c9&utm_medium=social&utm_source=twitter. com&utm_campaign=buffer. Accessed April 2017.

2. Burke BL, Hall RW. Telemedicine: pediatric applications. Pediatrics 2015;136(1):e293-308.

3. Plummer L, Allison C. The best pet trackers: GPS and smart collars for dogs and cats. Wareable. February 22, 2017. https://www.wareable. com/internet-of-things/the-best-pet-wearables-trackers-and-gps-fordogs-cats-and-more. Accessed April 2017.

Mia Cary Mia Cary, DVM, graduated with honors from the University of Florida College of Veterinary Medicine.

After working as an associate veterinarian in small animal private practice in Gainesville, Florida, she spent the next phase of her career as an industry veterinarian at Novartis Animal Health and then Boehringer Ingelheim. She has been on staff with the NAVC since February 2014 and currently serves as its Chief Collaboration Officer and Executive Director of the Veterinary Innovation Council. Dr. Cary is the 2017 President of the American Association of Industry Veterinarians and is on the Board of Directors for Pet Peace of Mind. She resides in Greensboro, North Carolina, with her husband, three bonus kids, and Lucy, the sweetest dog on the planet.

Aaron Massecar

BOX 2. VIC Veterinary Innovation Awards The VIC launched the first annual Veterinary Innovation Awards program in February 2017.

This program seeks to cultivate and celebrate innovation within the veterinary profession. The nomination phase for individual contributors and organizations ended May 1. To incorporate feedback from the community, a crowdsourced voting phase will continue from July 1 to September 30. Runners-up will be promoted throughout the profession, and the winners in each category will be announced at VMX 2018 in Orlando, Florida, where they will be invited to participate in an innovation-themed panel discussion. Visit VICAwards.com to cast your vote.

Aaron Massecar, PhD, is a faculty member of the College of Veterinary Medicine at Texas A&M and the Department of Philosophy at the University of Guelph.

He is a published author (Ethical Habits), speaker, coach, consultant, and project manager. His PhD research primarily focused on developing effective habits by making small interventions that result in major, longterm changes, which he uses in his current work with veterinarians looking to adapt to new trends within veterinary medicine. Dr. Massecar is also on faculty at Texas A&M and is helping develop the Veterinary Entrepreneurship Academy, a program to bring students, startup companies, faculty, and practicing veterinarians together. These student internships help train students in startup business principles and companies in creating tools that are custom built for veterinarians.

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VET REPORT VITALS

VET REPORT VITALS

What Does a Rise in Antimicrobial Resistance Mean?

Molly McAllister, DVM, MPH Banfield Pet Hospital, Portland, Oregon

shutterstock.com/Pressmaster

VET Report Vitals focuses on the results of the groundbreaking Banfield Veterinary Emerging Topics (VET) Report™ “Are We Doing Our Part to Prevent Superbugs? Antimicrobial Usage Patterns Among Companion Animal Veterinarians.” This report, a collaboration between the NAVC and Banfield Pet Hospital, aims to promote prudent antimicrobial use among companion animal practitioners by providing a baseline of antimicrobial usage data that can contribute to the discussion on how to achieve better concordance with published guidelines.

This article examines the issue of AMR within the larger “One Health” context by exploring the implications of AMR for veterinary practitioners, clients, and patients.

An upcoming article will discuss effective strategies for improving guideline concordance in daily practice.

IMPLICATIONS OF ANTIMICROBIAL RESISTANCE FOR COMPANION ANIMAL PRACTICE Antimicrobial resistance (AMR) arises when bacteria develop the ability to grow in the presence of antimicrobial drugs. This phenomenon is a natural evolutionary process of bacteria but develops more rapidly through misuse and overuse of antimicrobials.1

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VET REPORT VITALS

Resistance minimizes the medication options to treat bacterial infections and can challenge veterinarians’ ability to provide effective therapy.

Antimicrobial-resistant bacteria pose disease management concerns not only because resistant organisms can be directly transmitted between hosts, but also because resistance may be transmitted between bacterial species. Evidence indicates that antimicrobialresistant bacteria are transmitted bidirectionally between humans and household animals. This has implications for the health of companion animal patients, their owners, and their caretakers. Infection with resistant organisms can lead to longer and more severe infections, increased mortality, and higher costs for treatment.1,2 The growing threat of AMR has contributed to an increased scrutiny of antibiotic use practices in both human and veterinary medicine (Figure 1).

Given the importance of antimicrobial drugs in combatting infectious disease, the veterinary profession will undoubtedly continue to use antimicrobials to promote animal health.

However, given the implications for companion animal veterinary practice and public health, antimicrobial use will ideally become more judicious and specific to minimize AMR.

VET REPORT VITALS

THE IMPLICATIONS

WHAT DOES A RISE IN AMR MEAN?

Clients

Veterinarians

Less effective treatments for sick pets

Decreasing efficacy of available drugs

Increased veterinary bills

Threatens freedom to practice as we choose

Risk of AMR transmission from their pets

Zoonotic spread of AMR

FIGURE 1. The implications of antimicrobial resistance.

IMPLICATIONS FOR VETERINARIANS A large-scale implication of an increase in the incidence of antimicrobial-resistant infections is the potential for heightened scrutiny of antibiotic use in veterinary medicine, resulting from increased public awareness of AMR. Situations coming under particularly close inspection might include the use of antimicrobial drugs where not indicated; the administration of inappropriate drugs for a given condition; and prescription of antimicrobial drugs with inappropriate dosages, frequencies, or treatment durations.2 As evidenced by regulations on antimicrobial use in human and food animal medicine, it is also conceivable that companion animal veterinarians could be subject to restrictions on the types of antimicrobial drugs available for use in their patients, regulations around the use of specific drugs, and/or the requirement for approval to use certain drugs.3 Although directed primarily at drug manufacturers and distributors, legislation to ensure medicines are safe, effective, and of assured quality could certainly have consequences in the veterinary clinic, including changes in pricing, accessibility, and availability that would affect the use of certain drugs in treatment protocols.1 Additionally, the World Health Organization (WHO) has suggested optimizing the use of antimicrobial medicines in animal health through training or accreditation of health professionals to align with national legislation. This could include the creation of regulations around the licensing, distribution, and use of antimicrobial drugs and regulatory actions to preserve new antibiotics.1 It also implies that regulated use of antimicrobials in companion animal medicine, including greater control over dispensing rights, could become a reality.

In the face of the rise of AMR, advancement in the development of new drugs has been minimal. No major new class of antibiotics has been discovered since 1987, and few antibacterial agents are in development. As antimicrobial-resistant infections become more prevalent in companion animal practice, the consequences of infection with resistant microorganisms may include1: • Longer duration of illness (refractory to normal treatments) • Increased mortality • Prolonged treatment or hospitalization • Higher costs of care Evidence of the threat of AMR to veterinary and public health can be found in the recent discovery of a multidrug-resistant strain of Salmonella species infecting a cat presented to an Australian veterinary clinic for an upper respiratory tract infection.4 The strain was resistant to approximately 9 classes of antimicrobials, including carbapenems, which are frequently a last line of defense against multidrugresistant bacterial infections in humans. The infected cat was ultimately euthanized, and 3 of 8 other cats being treated at the clinic for unrelated illnesses subsequently tested positive for the bacterium, indicating that it was highly transferable. This is just a single example; the WHO reports that AMR is present worldwide, and drug-resistant bacterial strains include Escherichia coli, Staphylococcus aureus, and Mycobacterium tuberculosis.5 Last, but certainly of crucial importance, is the risk for transmission of antimicrobial-resistant infections from animals to their owners and caretakers, whether by zoonotic spread of transmissible disease or through transference of resistance among bacterial JULY/AUGUST 2017

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a successful veterinarian–client/patient relationship, veterinarians should consider these implications in decision-making and client communications.

Molly McAllister, DVM, MPH Dr. Molly McAllister is the Director of Research for the Banfield Applied Research and Knowledge (BARK) team at Banfield Pet Hospital. She is a graduate of Oregon State University College of Veterinary Medicine and subsequently earned her master of public health degree from the University of Minnesota. Dr. McAllister is passionate about the role of preventive and proactive care in the health and quality of life of our pets, as well as the intersection of human, animal, and environmental health. She lives with her family and 4 pets in Vancouver, Washington, where they spend as much time outdoors as possible.

species. Resistant Staphylococcus pseudintermedius was transmitted from pet to owner in Spain,6 and numerous multidrug-resistant zoonotic bacteria have been encountered in companion animal practices with the potential to be spread bidirectionally between humans and their pets.7 These reports provide evidence that companion animals provide a source of antimicrobial-resistant infections to—and are at risk for contracting them from—humans, making prevention or minimization of zoonotic spread a critical consideration for companion animal veterinarians.

IMPLICATIONS FOR CLIENTS AMR has important implications for veterinary clients as well. In the interest of promoting good compliance within

Banfield has always been dedicated to using its extensive data to provide insights to the profession on topics that can improve veterinary care for pets. The first annual Banfield Veterinary Emerging Topics (VET) Report, supported by the collaborative educational efforts of the NAVC, focuses on a critical topic: antimicrobial resistance. It is titled “Are We Doing Our Part to Prevent Superbugs? Antimicrobial Usage Patterns Among Companion Animal Veterinarians.”

“We are proud to team up with the NAVC on the 2017 VET Report to raise awareness about the critical topic of antimicrobial resistance in companion animal practice and how veterinarians can address it in their own practices,” said Dr. Karen Faunt, Vice President of Medical Quality Advancement at Banfield Pet Hospital.

The full report is available at Banfield.com/VETReport or VetFolio.com/VETReport.

Many of the issues that affect veterinarians will be of equal or greater concern for clients because they directly affect their pet and finances. These issues include less effective treatments for infections, which could ultimately lead to worse outcomes, with greater morbidity and mortality. In addition, decreased effectiveness of available treatments and prolonged therapy are likely to result in higher veterinary bills.

The WHO has shown that AMR is a drain on the global economy, with economic losses due to higher costs of treatment in human medicine. Although the significance of these costs in companion animal medicine is likely to be lower, the effect on the individual owner is likely to be more substantial.1 Finally, the reality of the risk for AMR transmission between clients and their pets is a topic that cannot be neglected in educating clients on appropriate antimicrobial use.6,7 In discussions of treatment options and plans with clients, conveying these longer-term implications may help improve client compliance.

SUMMARY A major challenge in the judicious use of antimicrobials can be the discrepancy between the visible and invisible effects on patient outcomes and resistance development, respectively. In the short term, immediate patient needs and client expectations can make the dispensation of antimicrobial drugs the easier solution. This may provide coverage in case of infection and avoid the hassle and burden of a client returning later for a prescription if preventive and supportive measures have not been effective. These effects are visible outcomes of antimicrobial use and occur relatively quickly after a patient presents to the veterinarian, so they are more likely to be associated in the minds of the veterinarian and the client.

The invisible consequences of AMR are the public health impacts, drug efficacy, and cumulative patient outcomes. Although serious, these consequences are often removed, both temporally and spatially, for the veterinarian and client, and therefore are harder to balance against the immediate, visible results. Keeping them in mind through education and conversation can help veterinarians balance their responsibilities as providers of treatment to pets in their care, including VET REPORT VITALS continued on page 30

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VET REPORT VITALS

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References: 1. Levy SA. 2002. “Use of a C6 ELISA test to evaluate the efficacy of a whole-cell bacterin for the prevention of naturally transmitted canine Borrelia burgdorferi infection.”

Vet Ther. 3(4):420–424. 2. Chu H., Chavez L. et al. 1992. “Immunogenicity and efficacy study of a commercial Borrelia burgdorferi bacterin.” J Am Vet Med Assoc. 201(3):403–411 3. Levy S., Lissman B. et al. 1993. “Performance of a Borrelia burgdorferi bacterin in borreliosis-endemic areas.” J Am Vet Med Assoc. 202(11):1834–1838. 4. Levy S., Millership J. et al. 2010.

“Confirmation of presence of Borrelia burgdorferi outer surface protein C antigen and production of antibodies to Borrelia burgdorferi outer surface protein C in dogs vaccinated with a whole-cell Borrelia burgdorferi bacterin.” Intern J Appl Res Vet Med. 8(3):123–128.

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HEARTWORM HOTLINE

AHS HEARTWORM HOTLINE

Turning Up the Heat on Heartworm Diagnosis Brian A. DiGangi, DVM, MS, DABVP American Society for the Prevention of Cruelty to Animals, Gainesville, Florida shutterstock.com/atiger

The Heartworm Hotline column is presented in partnership between Today’s Veterinary Practice and the American Heartworm Society (heartwormsociety.org). The goal of the column is to communicate practical and timely information on prevention, diagnosis, and treatment of heartworm disease, as well as highlight current topics related to heartworm research and findings in veterinary medicine.

Antigen testing for Dirofilaria immitis has been a foundational component of model preventive veterinary care for many years, particularly for dogs. For privately owned pets, the results of such testing guide prevention strategies and, in the event of a positive result, treatment for heartworm disease. In shelter populations, the results are often a key determining factor in the management of a dog throughout its stay in the shelter system, including its likelihood of a live release.

Although the accuracy of commercially available D immitis antigen test kits has been widely studied, recent reports have sparked renewed interest in the effect of antigen–antibody immune

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AHS HEARTWORM HOTLINE

complexes on test results.1–6 Such complexes can interfere with antigen detection, resulting in “no antigen detected” (NAD) test results in infected animals, and should be considered when NAD test results conflict with clinical expectations.

WHAT ARE IMMUNE COMPLEXES? Immune complexes represent soluble antigen bound to endogenous antibody, forming an insoluble unit that remains in circulation. Such complexes are a normal component of a functioning immune system and are cleared by phagocytosis when the balance of antigen to antibody in circulation is maintained. Excess immune complexes in circulation can result in tissue deposition, leading to local inflammatory responses and a variety of autoimmune diseases. Vasculitis, glomerulonephritis, pneumonitis, and arthritis are common sequelae of immune complex deposition in the respective affected organ system. In the case of diagnostic testing methods that rely on soluble antigen for detection (eg, enzymelinked immunosorbent assay, lateral flow assays), antigen bound in an immune complex may not be available for detection, leading to an NAD result despite the presence of antigen in the test sample.

A variety of techniques can be used to dissociate circulating immune complexes in a diagnostic sample.

HEARTWORM HOTLINE

Initial ELISA (no heat) Negative result

Sample treatment

ELISA after heat treatment Positive result

Antibody

Ag

Supernatant Heartworm antigen

Ag

Immune complex Serum

Heat plus EDTA

Precipitated antibodies

Antibody

© 2017 IDEXX Laboratories, Inc. All rights reserved. • 110441-00

FIGURE 1. Immune complex dissociation with sample pretreatment. Figure used with permission from IDEXX Laboratories, Inc. Ag, antigen; EDTA, ethylenediaminetetraacetic acid; ELISA, enzyme-linked immunosorbent assay.

Such techniques rely on denaturing proteins within the complex, allowing for precipitation of antibodies and subsequent freeing of the antigen (Figure 1). In laboratory settings, proteolytic enzymes (eg, pepsin), acid treatment (eg, ethylenediaminetetraacetic acid, citric acid), heat (104°C for 10 minutes), or a combination of these methods is frequently used for immune complex dissociation (ICD).

Heat pretreatment (HPT) of serum samples was standard practice in veterinary diagnostic laboratories through the mid-1990s and is still available upon request. However, the demand for simple, cost-effective, commercially available, point-of-care test kits led to its decreased use.

HOW DOES HEAT PRETREATMENT AFFECT DIAGNOSIS OF HEARTWORM INFECTION? In recent years, the effect of ICD in the form of HPT has been studied in diagnostic samples from cats and dogs.1–6 Such reports have demonstrated substantial increases in antigen detection in both species, resulting in greater diagnostic sensitivity (Table 1); however, the antigen detected cannot be identified as coming from living or dead heartworms. It follows that in dogs with heartworm disease that have received adulticidal therapy, a positive result on an antigen test with ICD does not indicate that the therapy was unsuccessful.

TABLE 1 Effect of Heat Pretreatment on Antigen Detection REFERENCE

POPULATION

STANDARD

HEAT

Ciucă et al 2016 1

194 Romanian stray dogs

8.2%

27%

DiGangi et al 2016 2

616 shelter dogs in United States

7.3%

12.3%

Drake et al 20153

15 owned dogs

0%*

53%

Gruntmeir et al 20154

34 owned dogs

0%*

67.4%

Little et al 2014 5

6 experimentally infected cats

17%

83%

Little et al 2014 6

220 shelter cats in United States

0.45%

5.9%

*Samples tested negative before study inclusion.

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Regardless of whether HPT is used in post-treatment testing, dogs should be tested for both antigen and microfilariae 6 to 12 months after completion of adulticidal therapy to assess treatment efficacy.

Many factors can affect detection of heartworm antigen in samples, leading to NAD results in truly infected dogs.

They include the stage of infection, concurrent medications (including doxycycline and heartworm preventives), and microfilarial status of the animal (Table 2).

Stage of Infection Although detection of D immitis is typically expected 7 months after infection (with earliest detection 5 months after infection),7 some evidence suggests that HPT may allow earlier antigen detection.

• In one study of experimentally infected dogs, 100%

of infections were detected after HPT of test samples obtained 4 months after infection.8 When samples were obtained 5 months after infection, only 42.6% of infections were detected in samples without HPT, while 100% of those infections were identified after HPT.8

• In another study of experimental infection in dogs,

positive antigen test results were obtained 31 to 36 days sooner in heated (days 127 to 132 after infection) versus unheated (day 163 after infection) serum samples.9

• In a study of experimental infection in cats, detection of heartworm antigen was possible as early as 5.5 months after infection when samples underwent HPT.5

The potential for earlier detection of heartworm antigen after HPT of samples from recently infected animals is theorized to be the result of a more robust immune response early after infection, along with the lower level of antigen produced by nongravid female worms, which both lead to greater immune complex formation and subsequent antigen blocking.

Heartworm Treatments Several studies have suggested that the administration of macrocyclic lactones and/or antibiotic therapy (eg, doxycycline) can affect immune complex formation and subsequently interfere with antigen testing.

• A study of 19 naturally infected dogs being managed

with monthly topical 10% imidacloprid plus 2.5% moxidectin along with oral doxycycline (10 mg/kg q12h for 30 days, every 6 months) demonstrated a substantial variation in timing of antigen detection between HPT and non-HPT samples.10 Among dogs that initially tested negative with non-HPT samples, antigen was detected in 50%, 95%, and 100% of dogs tested with HPT after 6, 12, and 18 months of therapy, respectively.

• Another report of 29 shelter dogs with antigen detection after HPT demonstrated 3.8 times greater odds of immune complex interference with test results when a history of macrocyclic lactone administration was reported.2

• Fifty-three percent of a cohort of privately owned dogs that had a negative antigen test result and received monthly macrocyclic lactones and doxycycline had detectable antigen after HPT of serum samples.3

There are a few possible explanations for the influence of macrocyclic lactone and doxycycline administration on immune complex interference with diagnostic test results. Although doxycycline has some antiinflammatory activity, administration of macrocyclic lactones and doxycycline in dogs with active heartworm infection is not adulticidal in the short term. The persistence of live heartworms allows for continued antigenic stimulation, subsequent inflammatory response, and antibody production in the face of a decreasing antigen load. Secondarily, use of these medications often results in sterilization of the female worms and subsequent decrease in antigen release.

These factors could contribute to a relative antibody

TABLE 2 Effect of Heat Pretreatment on Clinical Factors

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CLINICAL FACTOR

IMPACT OF HEAT PRETREATMENT

RATIONALE

Stage of infection

May allow earlier antigen detection

Immune response may be more robust immediately after infection, resulting in increased antibody production

Concurrent treatments (macrocyclic lactones, doxycycline)

May reduce frequency of negative test results in infected animals

Prolonged infection promotes continued inflammatory response in face of decreased antigen load, disrupting antigen-to-antibody ratio

Microfilariae

May reduce frequency of negative test results in infected animals

Circulating microfilariae promote continued inflammatory response and continued antibody formation

AHS HEARTWORM HOTLINE

PEER REVIEWED

excess, disrupting the normal clearance mechanisms and promoting continued immune complex creation.

Presence of Microfilariae The presence of detectable circulating microfilariae in canine blood samples also appears to influence the interference of immune complexes with antigen detection. Circulating microfilariae contribute to the chronic inflammatory response of heartworm disease and are therefore theorized to contribute to continued antibody production, allowing continued immune complex formation. One report of 26 shelter dogs with circulating microfilariae demonstrated 32 times greater odds of converting to a positive antigen test result after HPT compared with dogs that tested antigen negative both before and after HPT.2 Other reports have also identified circulating microfilariae in dogs whose test results converted from negative to positive after HPT.1,3,4 Interestingly, one of these reports included microfilariae of D immitis, Dirofilaria repens, and Acanthocheilonema reconditum,1 which suggests the potential for decreased specificity of antigen tests after HPT.

CAN I PERFORM HEAT PRETREATMENT IN MY CLINIC? A variety of veterinary diagnostic laboratories offer HPT panels upon request. In general, costs are minimal (<$30) and results are available within 1 to 3 days. Perhaps the biggest benefit of using diagnostic laboratories for HPT is the consistency and reliability of sample handling and testing techniques. Testing methods are typically validated and concomitantly run with positive controls to ensure accuracy of results.

antigen negative and microfilariae positive), when patients are receiving an alternative treatment protocol (eg, macrocyclic lactone and/or doxycycline), when the patient has known chronic inflammatory diseases (eg, pyoderma, otitis, endoparasitism), or when dogs test negative but originate from a known heartwormendemic region and have a history of lapsed or no preventive administration. An NAD result on a pretreated sample by a diagnostic laboratory can also rule out suspicion of heartworm infection.

BOX 1.

Simplified Heat Pretreatment Protocol 1. Dilute serum sample with approximately equal volume of 0.9% NaCl. 2. Place ~250 mL tap water into 500-mL glass beaker.

3. Microwave beaker to the point of boiling (approximately 2 min in 1000 W).

4. Remove heated water from microwave and place tube with diluted sample in the heated water for 10 minutes. (Note: Place serum in a glass collection tube and remove the rubber stopper before heating. Some warping of tube is expected.)

5. Repeat antigen test.

Diagnostic laboratory services are preferred, but when these are not available or feasible, a simplified HPT protocol has been successfully used (Box 1, Figure 2). In a study of shelter dogs, 616 samples underwent the simplified HPT protocol.2 Of these, 13 samples could not undergo repeat testing after heating. Five â&#x20AC;&#x153;untestableâ&#x20AC;? samples were presumed to be directly related to inconsistencies in the application of heat, resulting in solidification of the serum sample. The remaining 8 samples were untestable for a variety of reasons presumably unrelated to the heating protocol (eg, insufficient serum, invalid controls).

WHEN SHOULD I CONSIDER HEAT PRETREATMENT? Heat pretreatment is likely not indicated in most heartworm screening test scenarios. It should be considered when screening test results conflict (eg,

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AHS HEARTWORM HOTLINE

FIGURE 2. Diluted serum samples undergo a simplified heat pretreatment protocol. Note the use of glass tubes and the absence of rubber stoppers.

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VET REPORT VITALS VET REPORT VITALS continued from page 22

Brian DiGangi Brian DiGangi, DVM, MS, DABVP, is a senior director of shelter medicine for the ASPCA. He earned his DVM from the University of Florida and is board certified in both canine and feline practice and shelter medicine practice. He is a member of the board of directors of the Association of Shelter Veterinarians and the American Heartworm Society. Dr. DiGangi has published research on feline adoption, canine heartworm disease, and immunology. Prior to joining the ASPCA, he served as a clinical associate professor at the University of Florida.

In short, clinicians should consider HPT—as well as clinical staging with physical examination, complete blood count, blood chemistry analysis, urinalysis, and radiography—whenever there is a strong clinical suspicion of heartworm disease in the presence of negative screening test results. One report identified heartworm antigen in 64.7% of “negative” samples from patients for which the veterinarian’s clinical suspicion strongly supported heartworm infection.

The bottom line: There is no substitute for the clinical acumen of a veterinarian.

SUMMARY Immune complex interference is one factor clinicians should consider when interpreting the results of diagnostic tests that rely on antigen detection, especially when screening test results do not match clinical suspicions. Recent research has provided some insight into factors that can affect screening test results while identifying specific scenarios that may justify the added step of HPT of serum samples. These findings highlight the importance of adhering to the American Heartworm Society’s diagnostic testing recommendations. Annual screening for both antigen and microfilariae is the best way to identify heartworm infection as early and as consistently as possible.

provision of antimicrobial drugs when indicated, with their responsibilities as public health guardians.8

CLINICAL BOTTOM LINE The implications of AMR for companion animal veterinarians, their patients, and clients can be severe, including increased morbidity and mortality, longer illnesses, and increased costs.1 For veterinarians, there is a threat of restrictions and regulations around the types of antimicrobial drugs available and/or the requirement for approval to use certain drugs in our patients. For all involved, the growing threat of zoonotic spread of AMR is real and must be addressed proactively. Discussions of both the short-term and long-term implications of antimicrobial resistance in support of judicious use of antimicrobial drugs is a crucial behavior change for companion animal veterinarians to take to proactively address this growing issue.

References 1.

World Health Organization. Global action plan on antimicrobial resistance. 2015. www.wpro.who.int/entity/drug_resistance/resources/ global_action_plan_eng.pdf Accessed September 2016.

2. Weese JS. Investigation of antimicrobial use and the impact of antimicrobial use guidelines in a small animal veterinary teaching hospital: 1995–2004. JAVMA 2006;228(4):553-558.

3. Weese JS, Giguere S, Guardabassi L, et al. ACVIM consensus statement on therapeutic antimicrobial use in animals and antimicrobial resistance.

J Vet Intern Med 2015;29(2):487-498.

4. Gartry L. New salmonella superbug 'significant threat to public health'. ABC News. October 27, 2016. abc.net.au/news/2016-10-27/ new-salmonella-superbug-significant-threat-to-public-health/7968618.

Accessed November 2016.

5. World Health Organization. Antimicrobial resistance fact sheet.

September 2016. who.int/mediacentre/factsheets/fs194/en/. Accessed November 2016.

6. Lozano C, Rezusta A, Ferrer I, et al. Staphylococcus pseudintermedius human infection cases in Spain: dog-to-human transmission. Vector Borne Zoonotic Dis 2017;17(4):268-270.

7.

Damborg P, Broens EM, Chomel BB, et al. Bacterial zoonoses transmitted by household pets: state-of-the-art and future perspectives for targeted research and policy actions. J Comp Pathol 2016;155(1):S27-S40.

8. American Veterinary Medicine Association. Veterinarian's Oath. https:// www.avma.org/KB/Policies/Pages/veterinarians-oath.aspx Accessed October 2016.

To see the references for this article, please visit tvpjournal.com.

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VET REPORT VITALS

DERMATOLOGY DETAILS

DERMATOLOGY DETAILS

Dermatology Diagnostics: Cutaneous Biopsy Sarah Bartlett, DVM, MS, DACVD Animal Dermatology Clinic, Marietta, Georgia

Biopsy is often an important diagnostic step in determining the cause of cutaneous disease. An accurate diagnosis requires appropriate timing of the biopsy, careful site selection and biopsy technique, selection of a dermatopathologist, good communication between the clinician and the pathologist, and correlation of the results with the clinical picture.

In general, biopsy is indicated when a dermatosis is acute and severe, is unusual in appearance, or is not responding to appropriate therapy after 3 weeks.

Persistent ulcerations, suspected neoplasms, or vesicular dermatitis should always be biopsied. Biopsy should also be chosen for suspected conditions easily diagnosed by biopsy, such as follicular dysplasia, zinc-responsive dermatosis, sebaceous adenitis, and immune-mediated disease. Biopsy is also indicated in any suspected condition for which therapy is expensive, dangerous, or time consuming.1

SITE SELECTION At least 3 to 4 biopsy sites should be chosen, unless only a focal lesion is present. A variety of types of lesions should be sampled. Primary lesions, such as pustules, nodules, papules, vesicles, bullae, and tumors, are more likely to provide an answer.

However, secondary lesions may also be diagnostic,

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DERMATOLOGY DETAILS

especially crusts. Scale, comedones, alopecic areas, the margins of ulcers, and hypopigmentation (especially at the nasal planum or mucocutaneous junctions) may also be helpful. Typical locations for a suspected disease should be biopsied, but any atypical locations that are affected should also be included.

PREPARATION Timing of the biopsy is important. Active disease is required in order to obtain an accurate diagnosis, and in some cases lesions may be transient. If pemphigus foliaceus is suspected and pustules were previously present, it may be helpful to wait for pustule recurrence. In general, it is better to consider biopsy before the development of secondary changes that may cloud the diagnosis. Withdrawal of corticosteroids and treatment of bacterial infections for several weeks prior to taking biopsy samples is usually necessary to avoid masking of primary pathology.

Biopsies can often be performed without sedation.

However, sedation may be necessary to minimize patient movement and to increase patient comfort.

Biopsies from the nasal planum and paws almost always necessitate deep sedation or anesthesia. I often use a combination of dexmedetomidine and butorphanol for biopsy in these sensitive areas.

DERMATOLOGY DETAILS

Biopsy sites are typically outlined with a permanent marker as a guide for where lidocaine should be injected (Figure 1). The same marker may be used to draw a line in the direction of the hair growth to ensure proper orientation of the hair follicles when the sample is cut. This is most important for alopecic lesions, where the pathologist cannot determine the direction of hair growth by sight. Biopsy sites should never be scrubbed because diagnostic material may be removed. Gentle clipping may be necessary in long-haired patients; care should be taken not to let the clippers touch the skin surface.

Lidocaine 2% is typically used for local anesthesia.

This may be mixed with sodium bicarbonate in a 10:1 ratio to reduce the stinging sensation that lidocaine can cause. Inject lidocaine subcutaneously with a 25-gauge needle into the skin surrounding the lesion. Avoid injection into the dermis because it can cause an artifactual appearance of dermal edema. Do not inject lidocaine directly into lesions of the panniculus or if tissue cultures are to be performed. In these cases, use regional or general anesthesia. The total dose of lidocaine should not exceed 5 mg/kg in dogs or 2.5 mg/kg in cats.1 In small patients with many biopsy sites, the lidocaine may be mixed 1:1 with sterile saline to reduce the amount used, creating a 1% solution, which has also been shown to be effective.2

TECHNIQUE The sample may be obtained with a punch, incisional, or excisional biopsy.

Punch Biopsy Punch biopsies are most often performed, and typically a 6-mm punch is used. Reserve 4-mm punches for pinnae, the nasal planum, or footpads of small dogs and cats. Obtain punches from the center of a lesion unless it is an ulcer, and center small lesions within the punch.

Do not include any substantial amount of normal skin within the specimen because when the tissue section is cut in half at the lab the lesion may be missed. Use a fresh punch for each animal, and if the punch dulls during sample collection use a new one for subsequent punches. Dull punches cause tissue compression and artifact. Rotate the punch in one direction to prevent shear artifact. Decreased resistance is felt once the punch has reached the subcutis. Use a gauze square to blot any excess blood from the edge of the excised tissue; do not blot on top of the lesion. Once the

subcutis is reached, remove the punch and gently grasp the tissue section (do not squeeze) with tissue forceps or a 25-gauge needle, and cut the attachment with iris scissors (Figure 2). A single cruciate suture easily closes the defect left by a 6-mm biopsy punch.

Incisional and Excisional Biopsy An incisional elliptical biopsy is preferred for ulcers, vesicles, and bullae. The shearing force of a punch may damage vesicles and bullae, and the adjacent unaffected skin must be included for these lesions because the diagnostic tissue resides in the margin between affected and unaffected areas. Keep in mind that samples are cut in half longitudinally during processing. Incisional or excisional biopsies are performed for suspected disease of the panniculus and for tumors. A punch often does not reach deep enough to obtain the diagnostic sample for diseases of the panniculus.

Biopsy for Culture This article is primarily focused on biopsy for histopathology. However, in some cases, such as nodular disease, cellulitis, and diseases with fistulous tracts, biopsy for aerobic, anaerobic, and/or fungal culture may be needed. When fungal or unusual bacterial diseases (eg, mycobacteriosis, bacterial pseudomycetoma, actinomycosis, actinobacillosis, nocardiosis) are suspected, tissue biopsy specimens should be submitted and the lab should be notified of the suspected disorder. In these cases, disinfect the surface to avoid contamination with surface bacteria and observe sterile technique. Submit tissue in a sterile container, typically a plain blood

FIGURE 1. Permanent marker is used to outline the location of lidocaine injection for a punch biopsy.

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allow them to adhere for 30 to 60 seconds, and then place them upside down in the biopsy jar.

Samples from different locations can be placed into different jars or may be marked with ink or suture to differentiate them if needed. This is important when removing multiple tumors or when multiple processes are suspected. Separate crusts may also be included in the biopsy jar wrapped in lens paper.

Notify the pathologist that additional crusts have been submitted. If samples are mailed in the winter months, allow fixation for at least 12 hours before cold exposure.1 Contact the laboratory to determine if further fixation or additives are required.

FIGURE 2. A punch biopsy sample is grasped by the subcutaneous tissue, making sure not to crush the sample.

collection tube with a small amount of sterile saline added. Do not use lidocaine if a culture is going to be obtained from the biopsy specimen.

Lidocaine inhibits various gram-positive and gramnegative bacteria, mycobacteria, and fungi.3

Send samples to a veterinary pathologist specializing in dermatology or a veterinary dermatologist with expertise in dermatopathology. Ask your local dermatologist whom they would recommend in your area. Make sure to provide signalment, comprehensive history (including previous medications), examination findings, and differentials. Always include a lesion description and location on the animal.

Good-quality pictures can be helpful as well.

SAMPLE SUBMISSION

NEXT STEPS

Blot tissue samples to remove blood and immediately place the samples into the biopsy jar to avoid the desiccation that can rapidly ensue. Ten percent buffered formalin is the most commonly used fixative and must be used with a minimum of 10 parts formalin to 1 part tissue to ensure adequate fixation. Place elliptical or large punch specimens dermis side down on a piece of wooden tongue depressor or cardboard to prevent curling artifact,

A biopsy is merely part of a clinical workup and may not give a definitive diagnosis. However, even without a definitive diagnosis, some of the differential diagnoses may be eliminated or the results may establish a group of diseases to consider (eg, hormonal or allergic disorders). This information must then be combined with the patientâ&#x20AC;&#x2122;s history, clinical signs, and possibly additional testing to establish the diagnosis.

If the description provided by the dermatopathologist does not correlate with the clinical appearance of the lesions, consider that the clinical interpretation has been incorrect or that the biopsy specimens are not representative of the disease.4 Some cases will require repeat biopsy procedures because diagnostic lesions may not be present at the initial biopsy.

Sarah Bartlett Sarah Bartlett, DVM, MS, DACVD, graduated from the University of Florida College of Veterinary Medicine and completed an internship at Affiliated Veterinary Specialists in Maitland, Florida. She completed her dermatology residency at Animal Dermatology Clinic in Marietta, Georgia. She has recently returned to Animal Dermatology Clinic in Marietta after working in Florida for 2 years.

She is a member of the ACVD Credentials Committee, and her clinical interests include allergic and immune-mediated skin disease.

References 1.

Miller WH, Griffin CE, Campbell KL. Diagnostic methods. In Muller & Kirkâ&#x20AC;&#x2122;s Small Animal Dermatology, 7th ed. St. Louis: Elsevier, 2013, pp 92-95.

2. Henfrey JI, Thoday KL, Head KW. A comparison of three local anaesthetic techniques for skin biopsy in dogs. Vet Dermatol 1991; 2(1):21.

3. Williams BJ, Hanke CW, Bartlett M. Antimicrobial effects of lidocaine, bicarbonate, and epinephrine. J Am Acad Dermatol 1997; 37(4):662.

4. Shearer D. Dermatopathology. In Foster AP, Foil CS (eds): BSAVA Manual of Small Animal Dermatology, 2nd ed. Gloucester: BSAVA, 2003, pp 31-36.

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DERMATOLOGY DETAILS

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PRACTICAL PARASITOLOGY

The Flea-Infested Pet: How to Manage the Pet and Its Environment Cherie M. Pucheu-Haston, DVM, PhD, DACVD Louisiana State University School of Veterinary Medicine shutterstock.com/Helen Sushitskaya

Part 1 of this article—“The Flea-Infested Pet: Overview of Current Products” in the May/June 2017 issue—discussed important characteristics of today’s most commonly used flea control products. This follow-up article addresses key factors to consider in designing a flea control treatment program.

Individualization is the key: Although the products available today are an enormous improvement over those of bygone years, there is still no single product or protocol that is suitable for all situations.

Instead, designing an effective protocol requires the assessment of many patient, client, and environmental factors, in addition to knowledge about features of the products and the product formats themselves.

Table 1 provides an overview of available products.

FACTORS TO CONSIDER WHEN SELECTING A PRODUCT What Format Will Work Best for the Patient?

Spot-on Products Most products available today are topical spot-on preparations, which are easy to apply and do not require the owner to administer oral medications.

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However, these products have variable resistance to water immersion and bathing. In addition, some pets appear to be sensitive to the active ingredient or the vehicle itself and may develop dermatitis (ranging from mild scaling all the way to frank necrosis) at the site of application.1 Oral Products These products have the advantage of being completely waterproof, which makes them ideal for use in patients that swim or are bathed frequently. In addition, because they are not applied topically, they cannot rub off onto other animals, people, or furniture. They are also well suited for animals that may not tolerate application of spot-on formulations. However, almost all of them are chewable, flavored tablets. This flavoring may include ingredients such as beef, pork, or soy extracts, which may or may not be tolerated by food-allergic animals.

Vomiting may occur with any of the oral medications.

Collars Recently, a flea collar containing a combination of imidacloprid and flumethrin was released (Seresto, seresto.com). This collar is an easy, low-maintenance method of topical product application. Although the imidacloprid in the collar washes off, the collar replenishes it (this may take a toll on collar lifespan).2

PRACTICAL PARASITOLOGY

TABLE 1 Overview of Flea Control Products TRADE NAMES

WATER RESISTANCE

SAFETY IN CATS

LIFE STAGES AFFECTED

EFFICACY AGAINST TICKS?

SUITABLE FOR FOOD ALLERGIES?

Imidacloprid

Advantage II Advantage Multi Advantix

Variable, may not be sufficient in patients that swim or are bathed frequently

Yes, if not combined with permethrin (Advantix)

Adults, larvae

Only if combined with permethrin

Yes

Fipronil

Frontline, many others

Fair

Yes

Adults only (usually combined with an IGR)

Yes

Yes

Selamectin

Revolution

Should be very good beginning 2 h after bathing

Yes

Adults, larvae

Yes

Yes

Indoxacarb

Activyl Activyl Tick Plus

Moderate

Yes, if not combined with a pyrethroid (Activyl Tick Plus)

Adults, larvae

Only if combined with permethrin

Yes

Permethrin

Many

Probably moderate

No

Adults only

Yes

Yes

Flumethrin

Seresto

Continuously replenished from collar

Yes

Adults only

Yes

Yes

Dinotefuran

Vectra Vectra 3D

Moderate

Yes, if not combined with a pyrethroid (Vectra 3D)

Adults only (usually combined with an IGR)

Only if combined with permethrin

Yes

Spinetoram

Cheristin

Unknown

Yes (cats only)

Adults, eggs

No

Yes

Bravecto topical

Good, beginning 3 d after application

Yes

Adults

Yes

Yes

Comfortis Trifexis

Waterproof

Yes

Adults, eggs

No

Contains pork

Nitenpyram

Capstar

Waterproof

Yes

Adults only

No

Yes

Afoxolaner

NexGard

Waterproof

Not labeled for cats, but okay in households with treated dogs

Adults only

Yes

Contains soy

Adults only Fluralaner may also have some effects on larvae

Yes

Contains pork

ACTIVE INGREDIENT TOPICAL

Fluralaner ORAL Spinosad

Fluralaner

Bravecto

Waterproof

Not labeled for cats, but okay in households with treated dogs

Sarolaner

Simparica

Waterproof

Not labeled for cats, but okay in households with treated dogs

Adults only

Yes

Contains pork

Sentinel

Waterproof

Yes

Larvae, eggs

No

Contains pork

Methoprene

Many

Probably poor

Yes

Larvae, eggs

No

Yes

Pyriproxyfen

Many

Probably poor

Yes

Larvae, eggs

No

Yes

INSECT GROWTH REGULATORS Lufenuron

Manufacturer information for products not mentioned in text: Revolution— zoetis.com; Cheristin—elanco.us. IGR, insect growth regulator.

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The extended duration of action makes the product convenient to use but may also increase the likelihood of a client forgetting to replace the collar frequently enough for optimal control. In addition, some patients (notably cats) will not tolerate wearing a collar or may develop dermatitis underneath the collar.

Is Water Resistance Likely to Be an Issue?

This may not be a relevant question for most cats, but many dogs swim or are bathed frequently. Oral agents (eg, spinosad, afoxolaner, fluralaner, sarolaner) are completely waterproof, as are topical agents that rely on systemic absorption and distribution (selamectin).

Many topical agents may be removed by frequent bathing or water immersion or by bathing within 24 to 48 hours of application.3,4 Agents that are fairly water resistant include indoxacarb, deltamethrin, topical fluralaner, and dinotefuran; fipronil is partially water resistant.3,5 In my experience, imidacloprid has very poor resistance to water. The exception is the Seresto collar, in which the active ingredient still washes off but is replaced from the collar.

Is the Agent Effective on Immature Fleas?

Products that can kill or inhibit development of flea eggs or larvae prevent establishment of a selfperpetuating environmental population by fleas not killed by adulticides. Furthermore, the use of multimodal therapy may decrease the likelihood of the development of resistance. Some agents have inherent effects against immature stages, including spinosad (ovicidal), imidacloprid, selamectin, and indoxacarb (larvicidal).4,6,7 Other products may incorporate insect growth regulators (IGRs), such as lufenuron (found in Sentinel [sentinelpet.com]), methoprene (found in Frontline Plus [frontline.com]), and pyriproxyfen (found in Advantage II [bayerdvm.com] and Vectra [vectrapet.com]).

Is the Agent Safe to Use On or Around Cats?

Pyrethroids (synthetic pyrethrins; examples include permethrin and cyphenothrin) are often incorporated into combination flea control products to provide efficacy against ticks. However, with few exceptions, most pyrethroids are extremely toxic to cats.8 Exceptions include natural pyrethrin, flumethrin, and etofenprox.

A recent retrospective work by Malik et al reported

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several cats with pyrethroid toxicosis.9 In some cases, clients accidentally or knowingly treated cats with dogonly formulations. However, a few cases of toxicosis have occurred in cats that came into close contact with treated dogs soon after application. For this reason, it may be prudent to limit pyrethroid use (or use cat-friendly pyrethroids) if possible on dogs that live with cats or when using environmental treatments in homes with cats.

Does the Patient Have Known or Suspected Food Allergies?

All oral flea treatments available (except for Capstar) have some form of food-based flavoring. Comfortis (comfortis.com), Trifexis (trifexis.com), Sentinel Flavor Tabs, Bravecto (us.bravecto.com), and Simparica (simparica.com) contain pork protein; Sentinel Spectrum contains beef; and NexGard (nexgardfordogs.com) contains soy. Although individual food-allergic patients may be able to tolerate the small amount of food protein in these products, care should be taken to make sure that no other variables are changed when the product is instituted.

It is prudent to avoid the use of any flavored product during a food allergy elimination diet. However, because Bravecto lasts for 3 months, this product can be given at the beginning of an elimination diet; this should provide flea control for the duration of the diet trial.

Is Tick Control Also Needed?

Some active ingredients are efficacious against ticks (eg, fipronil, pyrethroids, afoxolaner, fluralaner, sarolaner), whereas other products may be formulated to include agents (usually a pyrethroid) that kills ticks (Advantix [bayerdvm.com], Vectra 3D, and Activyl Tick Plus [us.activyl.com]).

Are There Any Relevant Medical Issues or Concomitant Medications?

Most flea control products in current use have good margins of safety. However, there are a few conditions under which certain products might be best avoided.

Several oral flea control products should be used with caution in animals with preexisting seizure disorders (eg, spinosad, afoxolaner, sarolaner).6,10,11 Oral fluralaner is normally well tolerated by dogs with seizure disorders, but there is some indication that topical fluralaner may be more problematic in these patients.5 Concomitant use of spinosad and extralabel doses of ivermectin has been associated with the development of seizures, ataxia, twitching, and other neurologic signs.6

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FACTORS TO CONSIDER WHEN DESIGNING A CONTROL REGIMEN Is Specific Environmental Control Necessary?

Environmental flea control measures are not necessary in many circumstances if on-animal treatments are performed appropriately. Except in cases of very heavy environmental contamination, the regular application of adulticidal products (especially those using or incorporating products that also control against immature flea life stages) to all animals in the household provides good flea control in an acceptable period. In this case, the environmental flea burden is eliminated indirectly—fleas in the immature stages in the environment continue to develop, but the ensuing adults are killed before they can lay eggs or their eggs are rendered essentially infertile.

However, this may not be sufficient in cases of extremely heavy environmental infestation. Although on-animal treatments alone will eventually eliminate the flea population, it may take several months for the resident immature fleas to mature and be eliminated. In these cases, specific environmental control measures may help. Flea eggs are shed off of the animal and are most numerous where the animal rests. Therefore, frequent sweeping or vacuuming of the indoor environment and washing of the pet’s bedding helps decrease the number of eggs. Larvae are susceptible to desiccation, so they are typically found in cracks and crevices of floors or upholstery, or in relatively sheltered, moist areas, such as in carpets, in crawl spaces, or under shrubbery. Frequent vacuuming removes some of these larvae indoors.

In heavily contaminated environments, treatment of the premises with a product designed for environmental use may be of benefit. Examples include products containing IGR, such as methoprene or pyriproxyfen. Although these agents do not kill adult fleas, they should inhibit immature fleas from progressing to the adult stage. Some evidence suggests that indoor environmental treatment with borate dusts (Fleabusters RX, fleabusters.com) may have some larvicidal effects, although this is unlikely to be effective as a sole flea control agent.12,13 Several agents have been advocated for use in the management of contaminated outdoor environments, including the application of entomopathogenic nematodes (which are supposed to kill flea larvae), pyrethroid sprays, or sprays containing the ultraviolet light–stable IGR pyriproxyfen. However, no

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literature supports the use of nematodes as a flea control agent. Pyriproxyfen-containing agents do inhibit flea development but have no adulticidal properties. Finally, because of the widespread prevalence of pyrethroid resistance, these products may also have limited efficacy.14,15 Unfortunately, the best solution to minimize the effect of outdoor contamination is probably to limit access by pets and wildlife to “sheltered” areas that could support developing fleas. This may not always be feasible, which is one reason why aggressive on-pet treatment protocols remain the mainstay of effective therapy.

Are All the Animals in the Household Being Treated?

This would seem to be an easy question to answer, but the answer is not always so obvious. Clients may not volunteer the fact that they have (and are not treating) other animals, or they might think that some animals “don’t count” because they are not in direct contact with the treated pet. Many small pet mammals (such as ferrets and rabbits) may harbor fleas yet are often not considered during the development of flea control regimens.16 Pet dogs and cats that are allowed to roam freely will come into contact with flea-ridden animals and may become reinfested. Client education is very important in these circumstances. Owners must understand that almost any mammalian pet in the immediate environment can serve as a reservoir for fleas, regardless of whether the treated pet comes into direct contact with them, such as “outdoor-only” dogs and cats (including strays).

Free-roaming pets should ideally be confined to a more controllable area or at the least should receive very aggressive flea control. Some flea-allergic animals are so sensitive that roaming must be entirely curtailed.

Another source of environmental contamination is wildlife. Numerous species of small wildlife (including raccoons, opossums, and skunks) are able to carry fleas and perpetuate their life cycle. Although most pets do not come into direct contact with wildlife, they may have access to areas where these wild animals also go, such as crawl spaces under houses, under shrubbery, or in outdoor sheds and garages. Ideally, both the wildlife and the pet should be excluded from these locations.

CONCLUSION Despite the bewildering number of flea control choices available, a few quick questions about each patient can help narrow down the available choices to the 3 or 4 products best suited for your needs.

PRACTICAL PARASITOLOGY

Cherie Pucheu-Haston Cherie Pucheu-Haston, DVM, PhD, is an associate professor of veterinary dermatology and immunology at Louisiana State University School of Veterinary Medicine. She received her DVM from Louisiana State University and completed her residency at North Carolina State University (NCSU). She worked as a specialist in private practice for 7 years, then returned to NCSU to pursue a PhD in immunology. She is serving as the American co-chair of the International Committee on Allergic Diseases in Animals.

Her interests include the immunology of allergic skin and pulmonary diseases, as well as the immune response to fungal infections.

References 1.

Credille KM, Thompson LA, Young LM, et al. Evaluation of hair loss in cats occurring after treatment with a topical flea control product. Vet Dermatol 2013;24(6):602-605.

2. Stanneck D, Kruedewagen EM, Fourie JJ, et al. Efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs. Parasites Vectors 2012;5:102-108.

3. Vectra 3D product label. Lenexa, KS: Ceva Animal Health, 2013.

4. Advantage Multi prescribing information. Shawnee Mission, KS: Bayer Animal Health, 2015.

5. Bravecto prescribing information. Madison, NJ: Merck Animal Health, 2016.

6. Comfortis prescribing information. Indianapolis, IN: Elanco Animal Health, 2014.

7. Revolution prescribing information. Kalamazoo, MI: Zoetis, 2014.

8. Plumb DC. Plumb's Veterinary Drug Handbook. Stockholm, WI: PharmaVet, 2015.

9. Malik R, Ward MP, Seavers A, et al. Permethrin spot-on intoxication of cats Literature review and survey of veterinary practitioners in Australia. J Feline Med Surg 2010;12(1):5-14.

10. NexGard prescribing information. Duluth, GA: Merial, 2015.

11. Simparica prescribing information. Kalamazoo, MI: Zoetis, 2015.

12. Hinkle NC, Koehler PG, Patterson RS. Larvicidal effects of boric acid and disodium octaborate tetrahydrate to cat fleas (Siphonaptera: Pulicidae). J Med Entomol 1995;32(4):424427.

SIZE ORDERING CODE 5½ 6 6½ 7 7½ 8 8½ 9

13. Klotz JH, Moss JI, Zhao R, et al. Oral toxicity of boric acid and other boron compounds to immature cat fleas (Siphonaptera: Pulicidae). J Econ Entomol 1994;87(6):15341536.

14. Bossard RL, Dryden MW, Broce AB. Insecticide susceptibilities of cat fleas (Siphonaptera: Pulicidae) from several regions of the United States. J Med Entomol 2002;39(5):742-746.

7821PF 7822PF 7823PF 7824PF 7825PF 7826PF 7827PF 7828PF

15. Lemke LA, Koehler PG, Patterson RS. Susceptibility of the cat flea (Siphonaptera: Pulicidae) to pyrethroids. J Econ Entomol 1989;82(3):839-841.

16. Rust W, Dryden M. The biology, ecology and management of the cat flea. Ann Rev Entomol 1997;42:451-473.

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2017.2780-MFX_NA_MED_Todays_Veterinary_Practice_July_HPAd-outlined.indd 1

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Gastric Dilatation and Volvulus: Stabilization and Surgery Desiree Rosselli, DVM, DACVS (Small Animal) VCA West Los Angeles Animal Hospital, Los Angeles, California

Gastric dilatation and volvulus (GDV) is an acute, life-threatening disorder in dogs, characterized by abnormal twisting of the stomach on its mesenteric axis, with subsequent gastric gas accumulation and distention.

Sequelae of GDV can include decreased venous return to the heart, hypovolemia, gastric ischemia, systemic hypotension, myocardial injury, portal hypertension, shock, sepsis, and disseminated intravascular coagulation.

SIGNALMENT AND PRESENTATION Large and deep-chested dog breeds are considered to be the most at risk for GDV, including the German shepherd, Great Dane, standard poodle, Saint Bernard, Doberman pinscher, Irish setter, and Weimaraner.1 Even medium- and small-breed dogs with a deep chest conformation, including shar-peis, basset hounds, and cocker spaniels, can develop GDV. Most patients are middle-aged to older, and incidence of GDV increases with increasing age.2 The most commonly reported potential risk factors for GDV are listed in Box 1.2–9

Clinical signs can include restlessness or pacing along with nonproductive vomiting or retching. Ptyalism, abdominal distention,

BOX 1. Risk Factors Associated With Development of GDV2–9 • Large- or giant-breed dog •D eep chest conformation (increased thoracic depth-to-width ratio) • Increasing age •F amilial history, particularly having a first-degree relative with a history of GDV • Previous episode of gastric dilatation •P reexisting gastrointestinal disease or gastric foreign body • History of previous splenectomy • Large volume of food fed once daily • Eating a meal quickly • Dry dog food • Eating from a raised food bowl • Anxiety or stress

A BIG DEAL Large and deep-chested dog breeds are considered to be most at risk for gastric dilatation and volvulus.

shutterstock.com/Igor Boldyrev

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weakness, or collapse may be observed. Dogs can present anywhere on a spectrum of clinical signs, from alert and wagging their tail, with normal pulse quality and only mild abdominal distention, to collapsed, in decompensated shock, or even dead.10

DIAGNOSTIC TESTS Abdominal radiography, particularly the right lateral projection, is diagnostic for GDV. A healthy dog typically has no gas in the pylorus in right lateral recumbency. Conversely, in a dog with GDV, the stomach is dilated with gas, and radiography depicts the hallmark sign of compartmentalization (the “double bubble”) that signifies craniodorsal displacement of the pylorus, as shown in Figure 1. Ideally, an orthogonal projection (dorsoventral view) is also acquired, depending on patient stability. Presence of pneumoperitoneum suggests gastric rupture.

Ideal blood analysis consists of complete blood count, serum chemistry, and a coagulation profile. Efficiently obtaining the results from these diagnostic tests is sometimes not possible; therefore, point-of-care assessment is often more practical: packed cell volume/ total solids; blood glucose; and venous blood gas, including electrolytes and lactate. Lactate, a marker of hypoperfusion and anaerobic metabolism, has been evaluated as a prognostic tool in patients with GDV. Study findings are summarized in Table 1.11–14 Overall, higher lactate values are more suggestive of gastric necrosis and have a negative correlation with survival, particularly if hyperlactatemia does not substantially

FIGURE 1. A 12-year-old male neutered German shorthaired pointer presented for abdominal distention and acute-onset retching. This right lateral abdominal radiograph shows compartmentalization and craniodorsal displacement of the pylorus, the hallmark sign of GDV.

improve after fluid resuscitation. Regardless of the lactate value, surgical intervention is always recommended.

Blood pressure and electrocardiography (ECG) are useful diagnostic tools to assess patient stability, monitor effectiveness of volume resuscitation, and evaluate for cardiac arrhythmias (see Preoperative Treatment and Stabilization).

Thoracic radiographs can also be obtained in the preoperative period. Historically, this has been recommended in older patients to check for thoracic

TABLE 1 Prognostic Variables Associated With Plasma Lactate STUDY

SURVIVAL

GASTRIC NECROSIS

de Papp et al, 1999 11 ; 102 dogs

99% survival with lactate <6 mmol/L

Median lactate was 6.6 mmol/L in dogs with gastric necrosis

58% survival with lactate >6 mmol/L

Median lactate was 3.3 mmol/L dogs without gastric necrosis

Zacher et al, 2010 12 ; 64 dogs

23% survival with final lactate >6.4 mmol/L 10% survival with absolute change in lactate ≤4 mmol/L 15% survival with percentage change in lactate ≤42.5%

Green et al, 2011 13 ; 84 dogs

Significant relationship with initial lactate <4.1 mmol/L for predicting survival

Significant relationship with initial lactate >2.9 mmol/L for predicting gastric necrosis

Decrease in lactate ≥50% in 12 h was good indicator for survival Beer et al, 2013 14 ; 78 dogs

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Initial lactate ≥7.4 mmol/L was 88% accurate for predicting outcome

GASTRIC DILATATION AND VOLVULUS

Initial lactate ≥7.4 mmol/L was 82% accurate for predicting necrosis

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metastasis or other comorbidities, particularly if owners are having difficulty deciding whether to pursue surgery.

One study found a negative association between survival and the presence of cardiomegaly, despite a low incidence of pulmonary nodules, demonstrating the prognostic utility of preoperative thoracic radiography.15

PREOPERATIVE TREATMENT AND STABILIZATION For most patients, especially those that are severely affected, stabilization and treatment must be performed before or in conjunction with diagnostic testing. Immediate treatment goals are correction of hypovolemia and gastric decompression.

Box 2 summarizes therapeutic measures to consider during stabilization of a patient with GDV. Prompt vascular access is obtained with largegauge, short IV catheters (16 or 18 gauge). Cephalic veins or jugular veins should be used because of the lack of blood flow from the caudal half of the body. Initial volume resuscitation with a balanced isotonic crystalloid solution is recommended. Initial fluid volumes should be administered in rapid boluses of one-third to one-quarter shock volumes.

Monitoring perfusion parameters (Box 3) after fluid boluses is important in assessing response to therapy. Additional fluid boluses and addition of

BOX 2. Therapeutic Measures for Stabilization of Dogs With GDV • I V fluids: balanced isotonic crystalloids with or without colloids, hypertonic saline

synthetic colloid boluses or hypertonic saline may be required, depending on individual patient needs.

Gastric decompression should be performed as soon as possible. This can be achieved by passing a smooth-surfaced orogastric tube or via percutaneous trocharization. When an orogastric tube is passed in an awake patient, sedation (with a pure mu agonist opioid) is typically required, as is holding the patient’s mouth open with a roll of tape or gauze between the incisor teeth. Alternatively, the orogastric tube can be passed with the patient under general anesthesia; the presence of an endotracheal tube will help limit the risk for accidental aspiration of gastric contents.

Before an attempt to pass a gastric tube, the tube should be lubricated and premeasured to the level of the last rib. Twisting the tube when slight resistance is felt can facilitate passage of the tube into the stomach; however, caution must be used to avoid perforating the esophagus. When passing the gastric tube is difficult, decompression via trocharization may facilitate passage. After successful passage of the tube, observation of hemorrhage or mucosal tissue in the gastric contents can provide an index of suspicion of gastric necrosis and mucosal sloughing.

Trocharization can be performed in an awake or anesthetized patient: To perform trocharization, an area of skin on either side of the cranial dorsolateral abdomen should be clipped and aseptically prepared before puncture of the skin, body wall, and stomach with a large-bore needle (ie, 14 gauge) or over-the-needle catheter. The site of greatest distention or greatest tympany can be used. Gas and liquid may escape; pressure can be applied to the body wall to facilitate decompression.

•G astric decompression: orogastric intubation or percutaneous trocharization •A nalgesia: pure mu agonist opioid •A ntibiotics: broad-spectrum, particularly in patients with suspected gastric necrosis •A ntiarrhythmics if needed, lidocaine: can also serve as a free radical scavenger •C onsider procainamide or sotalol if lidocaine is ineffective

BOX 3. Parameters to Monitor for Effectiveness of Fluid Resuscitation • Mentation • Heart rate

•O xygen supplementation: particularly in patients with poor perfusion measures

• Peripheral pulse quality

•F resh frozen plasma: for patients with prolonged coagulation times

• C apillary refill time

• Drugs that reduce reperfusion injury: unknown efficacy

• Lactate

• Mucous membrane color • Blood pressure

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A rationale exists for the use of antibiotics in patients with GDV: there is the presumed risk for bacterial translocation with gastric mucosal compromise and increased mucosal permeability, as well as venous stasis and poor hepatic perfusion, likely resulting in inhibition of reticuloendothelial function.

depressants should be avoided. Typical premedications consist of a pure mu agonist opioid and a benzodiazepine, induction agents (such as etomidate or propofol), and an inhalant to maintain anesthesia. Monitoring of response to treatment and adjusting fluid therapy accordingly are still crucial during the intraoperative period.

Ventricular arrhythmias are reported in up to 40% of dogs with GDV; therefore, continuous ECG should be monitored.1 Ventricular arrhythmias that could decrease cardiac output or develop into ventricular fibrillation (specifically, ventricular tachycardia, R-on-T phenomenon, or multiform ventricular premature contractions) should be treated with IV lidocaine boluses initially, followed by a constant rate infusion if the bolus is successful in converting the rhythm to a sinus rhythm.

If lidocaine is not successful in converting the rhythm, procainamide or sotalol can be administered (Box 2).

SURGERY

Survival is positively affected by the time spent adequately stabilizing the patient; however, surgery should always be performed in a timely manner to limit the duration of splenic and gastric ischemia.

Other therapeutic modalities to consider include oxygen supplementation, especially in patients with signs of poor perfusion; fresh frozen plasma transfusion if indicated based on prolonged coagulation times or evidence of disseminated intravascular coagulation; or dextrose supplementation if a patient is hypoglycemic from septic shock. There may be a role for pharmacologic methods to reduce reperfusion injury, but consistent data on their efficacy are lacking.16

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Surgery has 3 goals: 1. Reposition the abnormally positioned stomach.

Typically, a clockwise volvulus has occurred; therefore, the fundus can be pushed dorsally while pulling the pylorus ventrally and toward the right.

2. Critically evaluate the abdominal viscera. Allow time for organs to reperfuse, and confirm correct gastric positioning. If necessary, perform partial gastric resection or splenectomy to remove necrotic tissue.

3. Perform a right-sided gastropexy to create a permanent adhesion between the pyloric antrum and the adjacent right body wall.

Gastric Repositioning A ventral midline celiotomy is performed. Adequate exposure is essential and the incision should extend from xiphoid to pubis. When the surgeon first enters the abdomen, the greater omentum is usually covering the stomach and should be gently retracted. Derotation of the stomach is facilitated by decompressing the gas distention, either by the anesthetist passing an orogastric tube or by the surgeon evacuating the air with a large-gauge needle.

The typical direction of volvulus is clockwise, with rotation of 180° to 270° being most common. In most cases, the stomach can be repositioned with the surgeon standing on the dog’s right side to push the fundus dorsally and to the dog’s left while simultaneously gently pulling the pylorus (located on the left initially) ventrally and toward the surgeon on the right.

When possible, complete fluid resuscitation (characterized by normalization of perfusion measures listed in Box 3) should be attempted before surgery because increased time from presentation to surgery has been associated with a lower mortality rate.17 Survival is positively affected by the time spent adequately stabilizing the patient; however, surgery should always be performed in a timely manner to limit the duration of splenic and gastric ischemia.

After repositioning, confirmation of normal gastric position is crucial. Although rare, a counterclockwise volvulus or a rotation through a rent in the splenic mesentery is possible, so the surgeon should always verify correct stomach positioning via careful observation and palpation of the gastroesophageal junction.

General anesthetic protocols vary depending on patient status; anesthetic agents that are arrhythmic or cardiac

There is often free peritoneal blood due to avulsion of the short gastric arteries and veins when the stomach distends and rotates. Bleeding has typically

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Evaluation of Abdominal Viscera

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ceased by the time of surgery, but if hemorrhage is ongoing, these vessels should be ligated.

Technique for Right Incisional Gastropexy

It is important to allow time for organs to reperfuse after gastric repositioning and before performing splenectomy or partial gastrectomy. The stomach should be palpated for any evidence of foreign material,4 and the entire stomach, especially the greater curvature and dorsal aspect, should be carefully evaluated for necrosis. Gastric necrosis is reported in 13% to 20.5% of patients.1,17–19 Necrotic areas can be identified by their black, grey/white, or green serosal color; thin texture on palpation; or lack of serosal capillary perfusion. If gastric necrosis is present, placement of stay sutures in visibly normal tissue helps to manipulate the stomach, plan gastric resection, and limit potential spillage of gastric contents into the abdomen.

Right incisional gastropexy is the most commonly performed technique because of its technical ease, low risk of morbidity, no need for additional instrumentation, and effective production of a permanent adhesion.24 The site of gastropexy is first planned by manually apposing the stomach to the body wall to ensure an anatomically appropriate site. To aid in visualization, the Balfour retractor can be removed, and assistants standing on the right side of the dog can retract the abdominal wall with towel clamps or Army-Navy retractors. The surgeon can change position at the table and stand on the dog’s left side for improved access for suturing.

Partial gastrectomy can be performed via resection and hand-sewn 2-layer closure or by using surgical stapling equipment. All nonviable tissue should be resected; normal tissue will have bleeding from the cut surface, particularly the muscularis layer. The appearance of the mucosal tissue should not be used to guide resection.

The limiting factor for the surgeon’s ability to perform resection is the anatomic location of necrosis and concern for esophageal lumen diameter, specifically when necrotic areas involve the cardia and esophagus.

An incision is made along the right body wall, completely through the transversus abdominis muscle. The incision can be oriented vertically or horizontally, as demonstrated in Figure 2. It is important for the incision to be

The need for splenectomy because of irreversible vascular devitalization or thrombosis is reported in approximately 16% to 22% of patients.17–19 A nonviable spleen has a spongy texture, lack of pulse in the splenic artery, and a black or grey color that does not improve after gastric repositioning. Splenectomy may be performed using ligation, stapling equipment, or vessel sealant devices.

Right-Sided Gastropexy A gastropexy is the creation of a permanent adhesion between the stomach at the level of the pyloric antrum and the adjacent right body wall. Numerous techniques for performing right-sided gastropexy for GDV are described, including incisional, belt-loop, circumcostal, ventral incision/incorporating, stapled, tube, and laparoscopic assisted. For successful adhesion formation, the muscular layers of the body wall and the stomach should be joined. Achieving an anatomically correct gastropexy is important to prevent potential complications, such as gastric outflow obstruction.20 No study has compared all the different techniques simultaneously; however, these techniques reportedly have similar rates of morbidity, adhesion formation, strength, and recurrence.21–23

A

B

FIGURE 2. These images depict the initial step in right incisional gastropexy in 2 separate patients. The cranial aspect of each dog is oriented to the right of the photograph. An incision is made through the transversus abdominus muscle on the right body wall, caudal to the last rib to avoid incising the diaphragm and dorsal enough to maintain an anatomic position. The incision can be oriented vertically (A) or horizontally (B).

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located caudal to the last rib to prevent penetration of the diaphragm and subsequent pneumothorax. The incision should be located dorsal enough to be in an anatomic position, as well as to avoid interference with abdominal closure or decrease risk for inadvertent damage to the stomach if future laparotomy is performed.

shorter than for patients treated surgically.10,21,25 Therefore, surgery should always be recommended.

In two studies,26,27 the rate of recurrence of GDV after gastropexy was 0%, but recurrence has been documented rarely.10,28 Occurrence of gastric dilatation after gastropexy is reported as 5% to 11%.21,25–27

Next, an incision of similar length is made in the seromuscular layer of the stomach at the level of the pyloric antrum. A location on the stomach without visible vasculature is chosen. Figure 3 demonstrates the completed incision and the ability to appreciate the difference between the seromuscular layer and the underlying mucosa/submucosal layer.

POSTOPERATIVE TREATMENT

Two rows of sutures are placed, typically in simple continuous fashion, beginning at the craniodorsal aspect of the respective incisions, as demonstrated in Figure 4.

The deep edge of the transversus abdominis incision is sutured to the deep edge of the gastric seromuscular incision, with care taken to make wide bites (at least 3 mm) on each side. Typical suture choice is a 2-0 monofilament long-lasting absorbable suture material.

After completion of the first suture line, a second suture line is performed in identical fashion to oppose the superficial or ventral aspect of the respective incisions.

The completed gastropexy is shown in Figure 5.

Postoperative treatment is typically a continuum of care from pre- and intraoperative therapy.

Continued volume resuscitation may include IV isotonic crystalloids (90–120 mL/kg/day); colloids, such as hydroxyethyl starch (10–30 mL/kg/day); and fresh frozen plasma or other blood products, depending on individual patient needs. For analgesia, injectable opioids are recommended. Nonsteroidal

A

RECURRENCE Without gastropexy, the rate of recurrence of GDV is 55% to 75%, and median survival times are significantly

FIGURE 3. The second step during right incisional gastropexy is an incision through the seromuscular layer of the stomach, at the level of the pyloric antrum. The incision can be made longitudinally (depicted) or transversely, taking care to avoid the prominent vasculature along the omental attachment to the stomach. In this image, the cranial aspect of the dog is oriented to the right and the underlying mucosal/submucosal layer of the stomach is differentiated with a forceps.

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B

FIGURE 4. In these images, the cranial aspect of the dog is oriented to the right, and the surgeon is standing on the left side of the dog to improve visualization and ease of suturing. In A, the suturing is started with the dorsal (deep) side of the respective incisions; suturing in a cranial-to-caudal direction is most efficient for a righthanded surgeon. In B, the dorsal (deep) side of the gastric seromuscular incision is sutured to the dorsal side of the transversus abdominus incision. Assistants standing on the dog’s right side can help improve visualization by retracting the abdominal wall with towel clamps and pushing in to provide tension on the body wall.

VETFOLIO WORK Sherri O’Brien, DVM VetFolio User Since 2015

Won her first year of VetFolio

Passion for feline medicine

See how Sherri puts VetFolio to work: Getting Started “We as veterinarians are good at multitasking. I can cook dinner, fold laundry or work out on my exercise bike while I listen to a class. I can even listen to a podcast while I am driving to an alumni event. The education comes to you!”

Staying Fresh “Our profession is constantly changing, and VetFolio allows you to engage in this change. If you have recently graduated, there are surgery videos and classes on the subjects you may have not covered deeply in school. If you have been out of school for over five years, VetFolio can help you stay current and academically fresh. We are never too old to learn!”

Becoming a Pro “Everyone has their own way that they prefer to learn. There are surgery videos, short podcasts, longer lectures, and articles at your fingers. You can choose how you take your educational adventure.”

Photo credit: Shira Marie Photography

Continuing the Experience “I use the information learned on VetFolio daily. There are a variety of topics that I incorporate into my daily discussions with clients, technicians and rescue groups.

Whether it has to deal with the pros and cons of early spay/neuter or the life expectancy of a dog with splenic HSA, the classes offer information that can be used in real-life practice. VetFolio also allows one to stay medically current and have access to the newest products coming out on the market!”

Making #Goals I truly try to obtain 100 hours of CE a year. At least 40 are at conferences. I look forward to going to the NAVC Conference every year.

Meet Keenan Smith Loves giving back to the veterinary profession

INDIVIDUAL AND PRACTICE SUBSCRIPTIONS AVAILABLE. SEE HOW VETFOLIO CAN WORK FOR YOU AT VETFOLIO.COM.

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anti-inflammatory drugs are avoided because of the decreased gastric perfusion associated with GDV and the high possibility of gastric ulcers.

Gastroprotectants, such as sucralfate, histamine-2 receptor antagonists, or proton-pump inhibitors, can be administered. Antibiotic administration for 2 to 3 days after surgery is often indicated based on the presumed risk for bacterial translocation.

Postoperative monitoring includes blood pressure, urine output, and emesis watch. Gastric atony and delayed gastric emptying can occur after gastric dilatation, so antiemetics or prokinetics can be administered if vomiting or regurgitation is observed postoperatively. Continuous ECG should be closely monitored because more than half to three-quarters of patients experience postoperative arrhythmias within the first 12 to 24 hours after surgery,17,19 although not all patients require antiarrhythmic therapy. Repeated blood analysis and electrolyte measurement help to guide fluid therapy. Rechecking coagulation profiles may be warranted in patients at risk for disseminated intravascular coagulation.

Desiree Rosselli Desiree Rosselli, DVM, DACVS (Small Animal), is a surgeon at VCA West Los Angeles Animal Hospital. She received her doctor of veterinary medicine degree from the University of California Davis. She completed a rotating internship at the University of Wisconsin-Madison, a surgical specialty internship at Dallas Veterinary Surgical Center, and a residency in small animal surgery at the University of Georgia. Following her residency, she was employed as a clinical instructor at the University of Georgia.

Food and water may be offered several hours after surgery to an awake, alert patient.

PROGNOSIS Animals treated surgically for GDV have an overall 10% to 28% mortality rate.1,10,16–19 Poor prognostic indicators include the following: • Lactate level not responding to fluid resuscitation12,13

A

• Need for splenectomy17–19 • Gastric necrosis and need for partial gastrectomy1,10,16–18 • Preoperative arrhythmias17,18 • Increased time between clinical signs and admission16,19 • Severity of physical condition at the time of presentation10 • Hypotension at any time during hospitalization19 • Peritonitis or sepsis19 • Disseminated intravascular coagulation19

SUMMARY

B

FIGURE 5. Completed right incisional gastropexy. In A, the cranial aspect of the incision is oriented to the right. B is a laparoscopic image after completion of a laparoscopicassisted right incisional gastropexy.

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The immediate goals of stabilization of a patient with GDV are fluid resuscitation to correct hypovolemia and gastric decompression to make the patient as stable as possible for anesthesia. Surgical goals are prompt gastric repositioning, critical evaluation of the abdominal viscera, and rightsided gastropexy. With timely surgery, the prognosis for most patients is fair. Negative prognostic indicators include gastric perforation, the need for splenectomy and partial gastrectomy, lactate levels that do not respond to fluid resuscitation, and preoperative arrhythmias.

To see the references for this article, please visit tvpjournal.com.

PROVEN. TRUSTED.

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1 Data on file Bronchi-Shield®, Elanco and the diagonal bar are trademarks owned by or licensed to Eli Lilly and Company, its subsidiaries or affiliates. © 2017 Eli Lilly and Company, its subsidiaries or affiliates USCACVDC00015

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Anaphylactic Shock: How to Effectively Diagnose and Treat Jennifer L. Lyons, MS, and Jordan R. Scherk, DVM, DACVECC Blue Pearl Veterinary Partners, Midvale, Utah

Anaphylaxis is defined as the acute onset of a hypersensitivity reaction causing the release of mediators from mast cells and basophils.

Anaphylaxis may be a life-threatening condition that can involve one or more organ systems.

Often, a specific cause for anaphylaxis is not known. Anaphylaxis may be brought on by anaphylactic or anaphylactoid reactions; treatment is the same regardless of reaction type.1,2

PATHOPHYSIOLOGY

Veterinarians are seeing an increasing number of anaphylaxis patients because of the range of substances patients are exposed to, such as vaccines, new medications, and those from outdoor physical exposures3 (see Specific Causes of Anaphylaxis). However, anaphylaxis is often misdiagnosed because definitive criteria to distinguish anaphylaxis from an allergic reaction are lacking.10 This article reviews anaphylaxis pathophysiology, diagnostic criteria, treatment, and clinical examples.

Anaphylactic Reaction: Immunologic IgE Mediated

Anaphylactic reactions are classified into 4 separate categories: type I, or immunologic IgE mediated; types II and III, which are immunologic IgE independent; and type IV, or nonimmunologic. Most anaphylaxis patients are likely to have type I reactions, but it is unclear why.2

In immunologic IgE-mediated reactions, patients do not show clinical signs at the initial allergen exposure. Upon reexposure, IgE antibodies are produced, and the allergen forms a “bridge” that crosslinks these antibodies via a high-affinity receptor, FcεRI, located in the membrane of mast cells and basophils. After binding,

BEES POSE AN ANAPHYLACTIC THREAT because the venom in their stings contains peptide 401, phospholipase A2, melittin, and hyaluronidase.

shutterstock.com/Irina Kozorog

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antibodies cause mast cell and basophil activation and start the immediate hypersensitivity reaction.

Cross-linking induces a membrane change, causing an influx of calcium ions into the cell that initiates degranulation and, thus, a release of mediators (eg, histamine). Interactions between mediators and host organs cause clinical signs to appear.2

Anaphylactoid Reaction: Immunologic IgE Independent In contrast, immunologic IgE-independent reactions occur through IgG antibody production. Allergen exposure activates IgG antigen binding to low-affinity receptors on macrophages. IgE-independent reactions require

Specific Causes of Anaphylaxis Hymenoptera Hymenoptera is an order of insects that includes bees, wasps, and ants. The venom of each species has different effects in patients.

Wasps and Hornets Wasps, unlike bees, have smooth stingers and may sting multiple times. They are much more aggressive than bees. Hornets defend their nests aggressively and have much more painful stings than either wasps or bees due to the amount of acetylcholine in their venom. Wasp and hornet stings contain the same proteins associated with bee venom with the exception of melittin. Bites and stings may produce a toxic envenomation response. The estimated lethal dose is 20 stings/kg. 5 Fire Ants Fire ants can be very aggressive. They attach to their prey with their mandibles and may sting with a nonbarbed stinger multiple times. Their venom contains hyaluronidase, phospholipase, and water-insoluble alkaloid compounds. Alkaloid venom causes cytotoxic, hemolytic pustules. Fire ants do not elicit an IgEmediated anaphylactic response but an anaphylactoid one. 6 Other Causes Other common causes of anaphylactic reactions include ophthalmic antibiotic ointment (in cats), drugs (some chemotherapy agents, contrast material, and antibiotics), and blood transfusions.

Ophthalmic Antibiotic Ointment in Cats In a retrospective evaluation of observed cases of anaphylaxis in cats that were administered a topical ophthalmic antibiotic, 56% of evaluated cats had anaphylactic reactions within 10 minutes. All ointments used contained polymyxin B. Clinical signs manifested in at least 2 body systems. Most commonly reported signs included respiratory and gastrointestinal compromise. Other organ systems involved were cardiovascular and cutaneous. Standard, symptomatic treatment aided in recovery; however, 13% of patients in this study died.7 Contrast Agents A case study of 3 canine patients recorded severity of anaphylactoid reactions to magnetic resonance imaging contrast media in anesthetized patients. Clinical signs ranged from very mild (cutaneous edema, which resolved during recovery) to severe (cardiovascular collapse, which necessitated swift emergency care). 8 Blood Transfusions IgE-mediated anaphylactic reactions may occur in patients receiving blood transfusions because of the presence of IgE and mast cells. Reported mild clinical signs include edema, urticaria, vomiting, and dyspnea. At onset of mild signs, the transfusion should be stopped. If the signs resolve in a timely fashion, the transfusion may continue at a slower rate (25%â&#x20AC;&#x201C;50%). If there is evidence of more severe clinical signs, the transfusion should be discontinued and emergency action taken. 9

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shutterstock.com/nutsiam

Bees Bees pose an anaphylactic threat because the venom in their stings contains peptide 401, phospholipase A2, melittin, and hyaluronidase. Peptide 401 is also known as mast cellâ&#x20AC;&#x201C;degranulating peptide and causes histamine release.

Phospholipase A2 works with melittin to cause intravascular hemolysis. Hyaluronidase changes vascular permeability by disrupting collagen and allowing other venom components to penetrate cells. Melittin hydrolyzes cell membranes, thus altering permeability. It also causes biogenic amines and potassium to leak from cells and induces catecholamine release. Melittin is the primary cause for localized pain. 4,5 A bee can only sting once because of the barbs on its stinger.

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more antigen exposure and do not result in the release of histamine as a mediator. Furthermore, IgE-independent reactions do not require initial allergen exposure.2,3

Anaphylactoid Reaction: Nonimmunologic Anaphylaxis Nonimmunologic reactions may occur via degranulation of mast cells and basophils without immunoglobulins.

They may be triggered by external influences, such as physical factors, drugs, and external toxins.2,3

CHEMICAL MEDIATORS Mediators stored in mast cells and basophils (ie, histamine, heparin, proteases such as tryptase and chymase, and cytokines) are released during degranulation

(Figure 1), which causes an increased production of phospholipase A and thus arachidonic acid and its metabolites. Downstream activation of this cascade leads to an increase in newly synthesized mediators, such as prostaglandins, leukotrienes, and plasma activating factor. These newly synthesized mediators induce an inflammatory response. The release of inflammatory and vasoactive mediators leads to shock.10,12

Histamine Once an antigen has bound to the primed IgE receptors, histamine is released. Histamine is the principal mediator stored in granules of mast cells and basophils. It is released quickly during anaphylaxis and can be found in elevated concentrations in circulating plasma less than 1 minute after allergen interaction.3

Mast cell activation and granule release

GI Tract:

Airway:

Blood Vessels:

Increased fluid secretion

Decreased diameter

Increased blood flow

Increased mucus secretion

Increased permeability

Increased peristalsis

Expulsion of the GI tract contents (vomiting and diarrhea)

Congestion and blockage of airway (wheezing, coughing, phlegm) Swelling and mucus secretion

Increased fluid in tissues causing increased lymph flow, fluid shifts to the interstitium

FIGURE 1. Effect of mast cell degranulation.11 GI, gastrointestinal.

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Histamine acts through 3 receptors (H1R, H2R, H3R) to promote signs of shock. H1R increases smooth muscle contraction, causing vasodilation and increased vascular permeability. It also stimulates the conversion of l-arginine into nitric oxide, which leads to vasodilation and therefore decreases venous return. H2R increases gastric acids, increases heart rate and ventricular contractility, and further promotes vasodilation. H3R inhibits norepinephrine release, thus increasing the degree of systemic shock. Without norepinephrine, vasodilation can persist and lead to clinical hypotension.

Clinical signs of histamine release include rhinitis, pruritus, dyspnea, hypotension, and tachycardia.13

Other Mediators Heparin is also released from mast cell granules. The release of heparin inhibits clot formation by decreasing clotting factors.13 This may lead to a hypocoagulable state and predispose a patient to clinical bleeding.

Cytokines, such as interleukin-4 and interleukin-13, are synthesized and released in response to the arachidonic acid cascade. The release of cytokines leads to an increase in cellular responsiveness to inflammatory mediators, up to 6 times normal.12 Prostaglandins released may cause bronchoconstriction, pulmonary and coronary vasoconstriction, and peripheral vasodilation.14 Clinically, airway obstruction, increased airway secretions, and decreased cardiac output may be noted (hypotension).

Platelet activating factor decreases coronary blood flow and myocardial contractility and increases pulmonary resistance, vasodilation, hypotension, and platelet aggregation.13,14 Decreases in myocardial contractility in conjunction with vasodilation can lead to profound hypotension.

ANAPHYLACTIC SHOCK Shock is a state of low blood perfusion to tissues that causes inadequate delivery of oxygen and decreased cellular energy production. Shock is often brought on by hypovolemia, maldistribution of vascular volume, or failure of the cardiac pump (cardiogenic shock). Anaphylactic shock results from massive vasodilation secondary to mast cell degranulation, histamine release, and the rapid release of inflammatory and vasoactive mediators.

Vasodilation in turn decreases the relative circulatory volume, decreasing perfusion and thus oxygen delivery

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to tissues. This leads to splenic contraction and tachycardia, and ultimately myocardial and cerebral hypoxemia, cardiovascular collapse, and death.12

Shock Organs Because of differences in immune response, smooth muscle anatomy, and antigen degradation rates, each species has different physiologic responses to anaphylaxis.12 Dog: Liver, Gastrointestinal System In dogs, histamine is primarily released from the gastrointestinal tract into the portal vein, thus leading to hepatic arterial vasodilation and an increase in arterial hepatic blood flow. In addition, histamine release into the portal system creates a large venous outflow obstruction that results in a hepatic vascular resistance increase of up to 220% of normal within seconds.15,16 As a result, venous return to the heart is decreased.

Reduced hepatic venous return to the heart decreases cardiac output and therefore contributes to hypovolemia and decreased oxygen delivery to the tissues. Because of decreased oxygen delivery and hypovolemic shock, common clinical signs include collapse and acute onset of gastroenteritis that is sometimes hemorrhagic.16 Cat: Lungs In cats, anaphylactic reactions are seen primarily in the lungs. Cats typically respond to allergens via profound bronchoconstriction. This leads to reduced blood oxygen levels, increased dissolved carbon dioxide levels, and decreased cardiac output. Acute hypoxemia can increase sympathetic tone, causing splenic contractions and eventually hemoconcentration.16

CLINICAL SIGNS Signs of anaphylaxis may be categorized based on the affected organ system: cutaneous, respiratory, cardiovascular, or gastrointestinal.16

Cutaneous Cutaneous signs are the most common initial clinical sign of an allergic reaction but may be a precursor for more severe reactions, such as anaphylaxis. If severe anaphylaxis has a rapidly acute onset, cutaneous signs may be absent. The most common cutaneous clinical signs include erythema, urticaria, pruritus, wheals, and angioedema. These signs are often short in duration.

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Respiratory Respiratory signs often result from laryngeal and pharyngeal edema, bronchoconstriction, and increased mucus secretion. They include dyspnea, bronchospasm, stridor, tachypnea, and coughing.

Cardiovascular Because of the intensity of vasodilation during anaphylaxis, hypotension is the primary cardiovascular sign. Hypotension is further exacerbated by fluid extravasation as vascular permeability increases; intravascular blood volume can decrease up to 35%, leading to both a hypovolemic and a distributive shock state.15 Tachycardia due to hypovolemia may also be present in anaphylaxis patients. Conversely, bradycardia may be caused by increased vagal reactivity.

Careful auscultation may reveal cardiac arrhythmias.

Signs of decreased perfusion may exist, including pale mucous membranes, increased capillary refill time, decreased pulses, hypothermia, and depressed mentation.

Because of vasodilation, injected or “brick red” mucous membranes may be noted on physical examination.

Gastrointestinal Gastrointestinal signs may include nausea, vomiting, and diarrhea. A recent study of 96 dogs revealed that during anaphylaxis, blood flow is altered throughout the liver (portal circulation) and gastrointestinal tract, and hepatocytes are directly affected,17 resulting in excessive leakage of alanine aminotransferase (ALT).

The ALT levels in this study increased in the first 12 hours and peaked 24 to 48 hours later. This study also revealed that changes in the gallbladder wall may be detectable on ultrasound evaluation almost immediately following an episode of anaphylaxis. Striations in the gallbladder wall (“halo effect”) may be seen because of inflammation as well as impaired venous drainage.17

Primary Clinical Signs in Dogs Cutaneous signs, such as urticaria, erythema, angioedema of the face and muzzle, hypersalivation, and pruritus, can be seen but may be subtle and short lived.2 Hemorrhagic enteritis caused by portal hypertension is one of the most commonly noted clinical antemortem signs as visceral pooling of blood in the intestines increases, leading to vomiting and diarrhea.12,16 As a result of the degree of liver involvement, dogs typically exhibit signs of

cardiovascular impairment due to hepatic venous congestion. Other common clinical signs include hypotension and cardiovascular collapse; dyspnea, bronchospasm, and stridor may be noted as well.

Primary Clinical Signs in Cats Cats typically exhibit respiratory and gastrointestinal signs. Respiratory distress is often the first sign exhibited. Cats’ clinical signs may also include hypersalivation, laryngeal swelling, edema, pruritus, and signs of hypovolemic shock.12,16 Cats are less likely than dogs to experience cutaneous effects.

DIAGNOSTIC CRITERIA Anaphylaxis may be difficult to diagnose and is often overlooked. Diagnostic differentials include severe asthma, a vasovagal event, and neoplasia, such as a pheochromocytoma or mast cell tumor degranulation.10 Rate of onset of clinical signs is an important diagnostic criterion. Anaphylaxis usually occurs within the first 30 minutes after allergen exposure and progressively worsens. However, a general rule of thumb is that the more quickly the signs manifest, the more severe the anaphylaxis will be. Box 1 presents criteria that can be used to assess the likelihood of anaphylaxis in a presenting patient.

BOX 1. Likelihood of Anaphylaxis12 Anaphylaxis is highly likely when any 1 of the following 3 criteria are fulfilled.

1. Acute onset of an illness with involvement of the skin, mucosal tissue, or both (ie, pruritus, edema, facial swelling), plus at least 1 of the following:

a. Respiratory compromise (ie, dyspnea, bronchospasm, stridor, hypoxemia)

b. Symptoms of end-organ dysfunction (ie, hypotension, syncope, incontinence)

2. Two or more of the following that occur rapidly after exposure to a likely allergen:

a. Involvement of the skin-mucosal tissue

b. Respiratory compromise

c. Reduced blood pressure or associated symptoms

d. Persistent gastrointestinal symptoms (ie, vomiting, diarrhea)

3. Reduced blood pressure after exposure to known allergen for that patient

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Clinical signs sometimes subside and acutely reappear after several hours. These are known as biphasic reactions and can increase mortality if they are not recognized and treated appropriately.18 Obtaining a detailed history about past allergic reactions, vaccinations, outside exposure, and previous medical ailments can be an important tool in diagnosing anaphylaxis.

TREATMENT Treatment of anaphylaxis is entirely based on clinical signs but should follow the guidelines for fundamental life support. Treatment should be initiated quickly and take priority over diagnostics because of the likelihood of rapid progression of clinical signs and increasing possibility of death.14,16 As with all life support treatment, rapid triage assessment, including airway, breathing, circulation, and mental status, is paramount.

Delays in treatment can lead to worsening outcomes.2 Immunologic and nonimmunologic hypersensitivity responses produce identical clinical signs and are thus treated the same.1,2

Airway If the patient presents in respiratory distress, it may be necessary to secure an airway. An endotracheal tube may be placed for patients with laryngeal swelling. If an endotracheal tube is not feasible because of swelling, a temporary tracheostomy tube may be placed surgically. Albuterol (a β-agonist) may help cause bronchodilation and decrease bronchospasm.

Pharmacologic Doses for all drugs discussed below are listed in Box 2.

Epinephrine As an α- and β-agonist, epinephrine is essential in the treatment of anaphylaxis. It has the following effects: • α-adrenergic effects. Vasoconstriction, which increases vascular resistance and thus blood pressure and coronary perfusion, and decreased edema, which leads to relief of upper airway obstruction • β1-adrenergic effects. Positive inotropic and chronotropic activity, leading to increased cardiac output • β2-adrenergic effects. Bronchodilation,

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leading to increased tissue oxygenation; also, the rate of adenosine triphosphate hydrolysis into adenosine monophosphate increases, which results in inhibition of histamine and cytokine release from mast cells and basophils, truncating the type 1 hypersensitivity reaction In total, epinephrine works to accelerate heart rate, increase cardiac contractions, decrease mast cell degranulation, and improve oxygenation through bronchodilation.19 Potential adverse reactions include ventricular arrhythmias; hypertension; tachycardia; and transient, mild effects, including pallor, tremors, and dizziness (in humans).2 Epinephrine may be administered via the endotracheal tube; via SC, IM, or IV routes; or as a continuous-rate infusion (CRI). Current recommendations state that an initial dose

BOX 2. Drugs Used in the Treatment of Anaphylaxis Epinephrine19 • 0.02–0.04 mg/kg via endotracheal tube • 0.2–0.5 mg (total dose) SC or IM • 0.01–0.1 mg/kg IV • 0.05 mcg/kg/min CRI Antihistamines20 • Famotidine: 0.5–1 mg/kg IV • Ranitidine: 0.5–2.5 mg/kg IV • Diphenhydramine: 1–4 mg/kg IM (dogs); 0.5 to 2 mg/kg IM (cats) Glucocorticoids21 • Dexamethasone-SP: 0.1–0.5 mg/kg IV • Prednisone: 0.5–1.0 mg/kg PO Bronchodilators16 • Albuterol: 1 to 2 puffs via inhaler; can be administered up to every 15 minutes as a 90-g/puff inhaler, up to 3 doses10 • Aminophylline: 5–10 mg/kg IM or slow IV Vasopressors16 • Norepinephrine: 0.01–1 mcg/kg/min IV CRI • Dopamine: 5–10 mcg/kg/min IV CRI • Vasopressin: 0.5–1.25 mU/kg/min IV CRI Anticholinergic16 • Atropine: 0.02–0.04 mg/kg IV

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of epinephrine may be administered IM. This can be repeated every 5 to 15 minutes.19 For the fastest and most profound effect, IV administration is recommended. If shock has developed, IV administration of epinephrine (bolus dose) followed by a CRI that can be titrated to effect is recommended.2,19 If IV epinephrine boluses appear to have little to no effect, a CRI may be started.20 Studies have shown that SC administration may provide a very delayed effect and is not recommended.

Antihistamines While pretreatment with antihistamines is widely practiced to prevent the onset of anaphylaxis, studies show that their use during anaphylaxis may not relieve serious clinical signs. However, they may be administered in an effort to downregulate the release of more mediators during treatment.20 Both H1 and H2 antihistamines act as inverse agonists, not competitive antagonists. Inverse agonists differ from competitive antagonists in that when they bind to the receptor, they induce an opposite response instead of simply not causing receptor activation. H1 antihistamines have a higher affinity for H1R and may act to stabilize the receptors. H1 antihistamines are most effective in treating localized allergic reactions and include diphenhydramine, chlorpheniramine, and cyproheptadine. H1 antihistamines cross the blood–brain barrier; therefore, they may cause central nervous system depression.

H2 antihistamines include famotidine, ranitidine, and cimetidine. Studies have shown that use of H1 and H2 antihistamines together relieved cutaneous symptoms of anaphylaxis more effectively.20 However, these drugs should never be substituted for epinephrine during anaphylaxis. They should be used as ancillary treatments to help reduce some of the cutaneous and gastrointestinal signs.

Glucocorticoids Glucocorticoids do not relieve initial clinical signs but may be used in long-term management of anaphylaxis. Clinical improvement is typically seen up to 4 to 6 hours after administration.

Glucocorticoids act to inhibit the inflammatory responses of the late-phase eosinophil response and inhibit the arachidonic cascade.4

Bronchodilators Albuterol, an inhaled β-adrenergic agonist, may be used to treat respiratory signs and to relieve bronchospasm. However, it does not replace the need for epinephrine because it has minimal α-adrenergic effect. Aminophylline, a phosphodiesterase inhibitor, may be useful for increasing amounts of cyclic adenosine monophosphate, which in turn increases the release of endogenous epinephrine and thus furthers the inhibition of mediator release.16 Aminophylline also directly relaxes smooth muscles in the bronchi and pulmonary vasculature.

Fluid Therapy Fluid therapy is useful in treating patients with hypotension. Severe decrease in blood volume secondary to permeability changes and vasodilation secondary to histamine and cytokine release make aggressive fluid therapy necessary.

Fluid therapy helps prevent cardiovascular collapse by increasing vascular volume.14,16 Basic guidelines for fluid therapy are as follows:16 • Crystalloids: 10- to 20-mL/kg boluses over 5 to 15 minutes; this can be repeated up to 90 mL/kg (dogs) or 60 mL/kg (cats) • Colloids: 5-mL/kg bolus; this can be repeated up to 20 mL/kg Volume resuscitation should be tailored to the patient’s clinical response. Improvement in perfusion parameters (mentation, mucous membrane color, capillary refill time), rectal temperature, heart rate, blood pressure, and lactate measurements can help determine whether resuscitation is adequate.

Oxygen When patients with respiratory or hemodynamic compromise are treated, high-flow oxygen should be administered via facemask, nasal cannula, or endotracheal tube.14,16

TREATMENT OF SEVERE ANAPHYLAXIS In some cases, a more aggressive approach may be needed for treatment of anaphylaxis. Patients with severe hypotension and/or bradycardia

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that is unresponsive to epinephrine and fluid resuscitation should be treated symptomatically with vasopressors and/or anticholinergics.

Vasopressors Use of vasopressors should be considered when epinephrine and fluid resuscitation fail to improve blood pressure. Vasopressors act to increase myocardial contractility and cause vasoconstriction.2,16 These effects may help to counteract the vasodilation and myocardial dysfunction that occur during an anaphylactic reaction.

Anticholinergics For patients with persistent bradycardia in which epinephrine does not aid in the treatment of bronchospasm, anticholinergics may be administered.2,16

SUMMARY Anaphylaxis is a severe condition that requires rapid emergency treatment. Because of the lack of definitive diagnostic criteria, it may be difficult to diagnose and is often overlooked. Rapid patient history and assessment are key in diagnosing and treating anaphylaxis.

REFERENCES 1. Kemp SF. Anaphylaxis: current concepts in pathophysiology, diagnosis, and management. J Allergy Clin Immunol 2001;22(4):611634.

2. Simons FE. Anaphylaxis. J Allergy Clin Immunol 2008;121(2 Suppl):S402-S407.

3. Kemp SF, Lockey RF. Anaphylaxis: a review of causes and mechanisms. J Allergy Clin Immunol 2002;110(3):341-348.

4. Golden DB, Moffitt J, Nicklas RA, et al. Stinging insect hypersensitivity: a practice parameter update 2011. J Allergy Clin Immunol 2011;127(4):852-854.e1-23.

5. Cowell AK, Cowell RL, Tyler RD, Nieves MA. Severe systemic reactions to Hymenoptera stings in three dogs. JAVMA 1991;198(6):1014-1016.

6. Mueller RS, Janda J, Jensen-Jarolim E, Rhyner C, Marti E. Allergens in veterinary medicine. Allergy 2016;71(1):27-35.

MONITORING Patients experiencing anaphylactic shock should be hospitalized for an observational period of 48 to 72 hours.16 Organs involved in the initial reaction may quickly deteriorate and should be monitored closely. These organ systems can experience a secondary or biphasic response.

7. Hume-Smith KM, Groth AD, Rishniw M, Walter-Grimm LA, Plunkett SJ, Maggs DJ. Anaphylactic events observed within 4 h of ocular application of an antibiotic-containing ophthalmic preparation: 61 cats (1993–2010). J Feline Med Surg 2011;13(10):744-751.

8. Pollard RE, Pascoe PJ. Severe reaction to intravenous administration of an ionic iodinated contrast agent in two anesthetized dogs. JAVMA 2008;233(2):274-278.

9. Gibson G. Transfusion medicine. In King LG, Boag A (eds): BSAVA Manual of Canine and Feline Critical Care. 2nd ed. Wiley; 2007:226.

10. Johnson RF, Peebles RS. Anaphylactic shock: pathophysiology, recognition, and treatment. Semin Respir Crit Care Med 2004;25(6):695-703.

11. Janeway CA, Travers P, Walport M, Shlomchik MJ. Immunobiology: The Immune System in Health and Disease. 6th ed. New York: Garland Science; 2004.

Jennifer L. Lyons Jennifer L. Lyons, MS, is a veterinary technician at BluePearl Veterinary Partners in Midvale, Utah. Before moving to Utah, she attended the University of California, Davis, for 6 years where she received a BS in animal biology and an MS in animal biology with a specialization in reproduction. Her interests include emergency triage, critical care, and endocrinology.

Jordan R. Scherk Jordan R. Scherk, DVM, DACVECC, is a staff criticalist and the medical director of BluePearl Veterinary Partners in Midvale, Utah. He graduated from Western University of Health Sciences, completed an internship at VCA Veterinary Special Center of Seattle, and completed his residency training at the University of Georgia. His interests include trauma, acute kidney injury disease, cardiac critical care, cardiopulmonary resuscitation (CPR), and mechanical ventilation. He has lectured on CPR, congestive heart failure, and respiratory distress, as well as anaphylaxis.

12. Sampson HA, Muñoz-Furlong A, Campbell RL, et al. Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol 2006;117(2):391-397.

13. Tucker A, Weir EK, Reeves TJ, Grover RF. Histamine H1 and H2 receptors in pulmonary and systemic vasculature of the dog. Am J Physiol 1975;229(4):1008-1013.

14. Finkelman FD. Anaphylaxis: lessons from mouse models. J Allergy Clin Immunol 2007;120(3):506-515.

15. Schadt JC, Ludbrook J. Hemodynamic and neurohumoral responses to acute hypovolemia in conscious mammals. Am J Physiol 1991;260(2 Pt 2):305-318.

16. Lee JK, Vadas P. Anaphylaxis: mechanisms and management. Clin Exp Allergy 2011;41(7):923-938.

17. Quantz JE, Miles MS, Reed AL, White GA. Evaluation of alanine transaminase and gallbladder wall abnormalities as biomarkers of anaphylaxis in canine hypersensitivity patients. J Vet Emerg Crit Care 2009;19(6):536-544.

18. Stark BJ, Sullivan TJ. Biphasic and protracted anaphylaxis. J Allergy Clin Immunol 1986;78(1 Pt 1):76-83.

19. Lieberman P. Use of epinephrine in the treatment of anaphylaxis.

Curr Opin Allergy Clin Immunol 2003;3(4):313-318.

20. Sheikh A, Ten Broek V, Brown SG, Simons FE. H1-antihistamines for the treatment of anaphylaxis: Cochrane systematic review. Allergy 2007;62(8):830-837.

21. Choo KJ, Simons E, Sheikh A. Glucocorticoids for the treatment of anaphylaxis: Cochrane systematic review. Allergy 2010;65(10):12051211.

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PEER REVIEWED

Anaphylactic Shock: How to Effectively Diagnose and Treat LEARNING OBJECTIVES

Upon finishing this article, readers will be able to define anaphylaxis and describe its mechanisms of action, list the chemical mediators involved, identify the different shock organs in different species, recognize clinical signs, and determine treatments for patients with anaphylactic shock.

OVERVIEW

This article provides an overview of anaphylaxis; the pathophysiology of its mechanisms of action, including mediators and shock organs; and treatment recommendations for a variety of clinical signs associated with anaphylactic shock.

The article you have read has been submitted for RACE approval for 1 hour of continuing education credit and will be opened for enrollment when approval has been received.

To receive credit, take the approved test online at vetmedteam.com/tvp.aspx (CE fee of $5/article).

1. Hepatic vascular resistance can increase to _____ of normal in dogs experiencing anaphylaxis. a. 120% b. 170% c. 300% d. 220%

6. Which of the following receptors, when activated, causes an increase in nitric oxide production? a. H1R b. H2R c. H3R d. H4R

2. What drug may be useful for treating bronchoconstriction as well as inhibiting mediator release? a. Ranitidine b. Aminophylline c. Diphenhydramine d. Dopamine

7. Patients recovering from anaphylactic shock should undergo an observational period of ______ hours. a. No observational period is needed b. 24 to 36 c. 36 to 48 d. 48 to 72

3. Which type of reaction requires an initial allergen exposure? a. IgE-mediated b. IgE-independent c. Nonimmunologic d. IgG-mediated

8. Intravascular blood volume may be decreased by _____ due to fluid extravasation. a. 15% b. 25% c. 35% d. 45%

4. When should an epinephrine CRI be started? a. Immediately upon presentation b. If fluid resuscitation does not increase blood pressure c. Never d. When IV epinephrine boluses have little to no effect

9. What are the primary shock organs in the dog and cat, respectively? a. Liver; spleen b. Liver; lungs c. Lungs; liver d. Spleen; liver

5. Wasp and hornet stings contain all of the following proteins except a. peptide 401. b. phospholipase A2. c. melittin. d. hyaluronidase.

10. Which drug acts as both an ι- and a β-adrenergic agonist? a. Vasopressin b. Atropine c. Albuterol d. Epinephrine

NOTE Questions online may differ from those here; answers are available once CE test is taken at vetmedteam.com/tvp.aspx. Tests are valid for 2 years from date of approval.

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IMAGING ESSENTIALS

IMAGING ESSENTIALS

Ultrasonography of Peritoneal and Retroperitoneal Spaces and Abdominal Lymph Nodes Clifford R. Berry, DVM, DACVR; Elizabeth Huyhn, DVM; and Danielle Mauragis, CVT University of Florida

Welcome to our series of articles on small animal abdominal ultrasonography. The initial articles provided an overview of basic ultrasonography principles and a discussion about how to perform a systematic scan of the abdomen. The rest of the series discusses ultrasound evaluation of specific abdominal organs/systems.

Read the other small animal abdominal ultrasonography articles published in Todayâ&#x20AC;&#x2122;s Veterinary Practice at tvpjournal.com.

The peritoneal and retroperitoneal spaces are assessed throughout the ultrasound examination of the entire abdomen. The abdominal lymph nodes (lymphocenters),

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which are located throughout the abdomen, drain specific regional organs and areas. This article reviews the normal ultrasonographic appearance of these structures in dogs and cats as well as commonly encountered abnormalities.

PERITONEUM AND RETROPERITONEUM Normal Findings Ultrasound examination of the peritoneal and retroperitoneal spaces involves evaluation of the falciform, mesenteric, and retroperitoneal fat as well as potential cavities within these areas for the presence of masses, gas, or fluid (Figure 1). Like the pleural space, the peritoneal

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FIGURE 1. (A) Long-axis view of an adult canine liver just to the left of midline. The falciform fat seen in the near field (ventral; arrow) is hypoechoic relative to the liver and has a coarse echotexture. (B) Long-axis image in the area of the spleen from the same dog. The mesenteric fat (arrow) is seen dorsal to the spleen and is hypoechoic relative to the spleen and coarse in echotexture. (C) Fat in the retroperitoneal space surrounding the left adrenal gland. The fat is relatively hyperechoic to the left adrenal gland (LA) and is coarse in overall echogenicity. The anechoic circle ventral to the midportion of the long axis of the left adrenal gland is the phrenicoabdominal vein (arrow). HM, hypaxial musculature; Spl, spleen.

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FIGURE 2. Anechoic focal effusion (arrow) from the abdomen of a normal 4-month-old dog. A transudate was identified on cytology.

FIGURE 3. Long-axis image of the cranial abdomen in an adult dog. Note the anechoic effusion separating the diaphragm and the spleen and liver.

space is a closed cavity with a serous mesothelial lining.1 A scant amount of physiologic peritoneal effusion, typically not seen on ultrasonography, is normal; this effusion serves as a lubricant for the peritoneal organs.

specificity: anechoic effusions can be exudates and echogenic effusions can be transudates (Figure 4).

Nevertheless, a pure or modified transudate typically appears anechoic with no echogenic foci suspended in the fluid.3–5 Intraperitoneal hemorrhage, inflammation, or neoplastic effusions typically appear echogenic with suspended echoes.3–5 With moderate to severe peritoneal effusion, artifacts are more readily apparent. These include refraction artifacts along curved surfaces with urinary bladder wall dropout at the area of refraction, distal acoustic enhancement (through-transmission), or side lobe artifacts (see “Physical Principles of Artifacts & False Assumptions” [May/June 2015]).

A small amount of anechoic peritoneal effusion can be seen in young puppies and kittens2 (Figure 2), but no effusion should be seen in healthy adult dogs and cats.3,4 The fat within the peritoneum (located primarily in the mesentery and falciform ligament) has intermediate echogenicity and a coarse echotexture (Figure 1).

Effusions Peritoneal effusions can be detected by the presence of anechoic fluid separating and/or surrounding normal abdominal structures (Figure 3). Peritoneal fluid accumulation in adult dogs and cats is considered abnormal. Peritoneal effusion should be evaluated with cytology as well as culture and antibiotic sensitivity testing if sepsis is suspected.

Determining the type of effusion based on its echogenicity is problematic because ultrasound lacks

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Focal effusions, compared with generalized effusion, can be seen in areas of focal organ pathology (eg, acute pancreatitis). Additionally, exudative effusions can incite an inflammatory response resulting in increased echogenicity of the surrounding peritoneal or retroperitoneal fat6 (Figure 5). In all cases of significant effusion, the echogenicity of the peritoneal and retroperitoneal fat is increased due to throughtransmission or distal acoustic enhancement.

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FIGURE 4. Protein-losing enteropathy and hypoalbuminemia causing a pure abdominal transudate in a 12-year-old dog. (A) Multiple curvilinear areas of anechoic peritoneal effusion can be seen (arrows). (B) Echogenic effusion (arrow) secondary to hemorrhage from a splenic mass rupture. (C) Hyperechoic, hyperattenuating mesenteric fat (MF) with distal acoustic dropout due to attenuation (arrow) surrounding an inflamed, enlarged, hypoechoic pancreas (PA). In addition a mild echogenic effusion is seen surrounding the pancreas.

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FIGURE 5. Effusion dorsal (far field, arrow) to the urinary bladder in a dog with ascites caused by right heart failure.

If a small amount of peritoneal effusion is noted, focal collections of fluid may be seen first in the area of the liver (surrounding the hepatic lobes or gallbladder) or at the level of the cranial pole of the urinary bladder in the caudal abdomen (Figure 4A). These areas should be scrutinized selectively when a small amount of effusion is suspected.

In cases of inflammatory or neoplastic effusion, the mesenteric fat can become hyperechoic and hyperattenuating, as is seen in small animals with pancreatitis or carcinomatosis (Figure 4B and 4C). Acute renal disorders can also result in a perinephric effusion and hyperechoic retroperitoneal fat7 (Figure 6). Neoplasia of the retroperitoneal space has been reported (hemangiosarcoma, undifferentiated carcinoma, extra-adrenal or adrenal pheochromocytoma).3,4

Disseminated Abdominal Neoplasia Peritoneal effusion in cats and dogs may be secondary to carcinomatosis. In cats, the common sites of primary neoplasia resulting in peritoneal invasion and involvement are the pancreas, liver, and intestinal tract.8 In dogs, sarcomatosis is most commonly secondary to ruptured splenic or hepatic hemangiosarcoma with peritoneal seeding9 (Figure 7).

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FIGURE 6. Long-axis ultrasound image of the left kidney from a dog with acute renal failure secondary to leptospirosis. There is a perinephric effusion (arrow).

Pneumoperitoneum Common causes of pneumoperitoneum include rupture of a hollow viscus (typically gastrointestinal tract) or a penetrating wound. Small-volume pneumoperitoneum can be difficult to identify on ultrasound because the probe must be positioned on top of the free air for the air to be visualized.10 Characteristic features of a pneumoperitoneum include gas and associated artifacts outside the gastrointestinal tract (Figure 8).

Nodular Fat Necrosis Nodular fat necrosis is an incidental finding in cats (primarily) and dogs that appears as an oval structure within the peritoneal space. Such structures are mineralized and therefore have a curvilinear hyperechoic boundary and distal acoustic shadowing.11 They usually appear singly and can be found anywhere in the peritoneal (and, to a lesser extent, pleural) cavity (Figure 9).

ABDOMINAL LYMPH NODES (LYMPHOCENTERS) Abdominal lymph nodes can be divided into the parietal nodes (periaortic, renal, medial iliac, internal

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FIGURE 7. Diffuse peritoneal nodules from 3 different animals. (A) A cat with carcinomatosis due to pancreatic adenocarcinoma.

Multiple hypoechoic nodules are noted throughout the mesentery. (B) A dog with sarcomatosis secondary to peritoneal spread of hemangiosarcoma after rupture of a splenic hemangiosarcoma. Multiple hypoechoic nodules were noted adjacent to the jejunum within the mesentery (arrow). (C) A dog with lymphomatosis secondary to multicentric lymphoma. The heteroechoic to hypoechoic nodules (arrows) were within the mesentery and separate from the mesenteric lymph nodes that were also enlarged.

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iliac, and sacral) and visceral nodes (hepatic, splenic, gastric, pancreaticoduodenal, jejunal, ileocolic, and colic).3,4 A number of abdominal lymph nodes are not routinely seen on ultrasonography.

Abdominal lymph nodes vary dramatically in size and shape depending on the age of the animal and the location of the node.12 Assessment of abdominal lymph nodes requires the sonographer to understand the normal anatomic location of the individual nodes as well as the regional anatomy, particularly the vascular anatomy, because lymph nodes are found surrounding specific abdominal vessels.6,13â&#x20AC;&#x201C;16

Parietal Nodes The medial iliac lymph nodes are found caudal to the deep circumflex arteries along the lateral margins of the origins

FIGURE 8. Static ultrasound image from a dog with a pneumoperitoneum (arrows) with focal reverberation artifacts secondary to soft tissue-gas interface. This pneumoperitoneum was secondary to duodenal ulcer perforation from nonsteroidal anti-inflammatory drug administration.

of the left and right external iliac arteries from the aorta (aortic trifurcation). These nodes are located immediately cranial to, at, or just caudal to the trifurcation of the caudal abdominal aorta.16 They can be dorsolateral, lateral, or ventrolateral to the caudal abdominal vasculature.

To identify medial iliac lymph nodes, therefore, it is necessary to sweep the transducer in a dorsoventral direction while imaging the vessels in long axis.

Translation motion in the transverse plane while imaging the caudal aorta at the level of the trifurcation is also very useful to identify these nodes, often using a paralumbar acoustic window.

In larger dogs, the medial iliac lymph nodes are typically 2 to 4 cm in length. They can be seen as fusiform to oval in shape and are isoechoic to slightly hypoechoic (relative to the surrounding fat) with a faint outer hyperechoic capsule.

These nodes can be evaluated in long-axis (sagittal) or shortaxis (transverse) view (Figure 10) and are usually 3 to 5 mm in thickness in the adult dog.2 The medial iliac lymph nodes receive afferent lymphatics that drain the caudal abdomen, pelvis, tail, and pelvic limbs. Features of malignancy that have been described include enlarged, round, hypoechoic to anechoic internal echogenicity with little echotexture.17 In addition, focal effusion or hyperechoic fat may surround the abnormal lymph node in dogs.17

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FIGURE 9. A focal hyperechoic nodule with distal acoustic shadowing from a focal area of nodular fat necrosis with resultant dystrophic mineralization (arrow).

FIGURE 10. (A) Long-axis image of a normal mesenteric lymph node (arrow) from a dog with a normal abdominal ultrasound and no clinical signs. (B) Short-axis image of the medial iliac lymph node (arrow) in the same dog. The node is highlighted (+) to show the normal width. Ao, aorta, Cvc, caudal vena cava.

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Clifford R. Berry Clifford R. Berry, DVM, DACVR, is a professor of diagnostic imaging at University of Florida College of Veterinary Medicine. His research interests include cross-sectional imaging of the thorax, nuclear medicine, and biomedical applications of imaging. He received his DVM from University of Florida and completed a radiology residency at University of California–Davis.

Elizabeth Huynh Elizabeth Huynh, DVM, is a diagnostic imaging resident and graduate student at University of Florida College of Veterinary Medicine. Her interests include ultrasonography, cross-sectional imaging, and nuclear medicine. She received her DVM from Ross University, finished her clinical year at Ohio State University, and completed a diagnostic imaging internship at Animal Specialty and Emergency Center in Los Angeles, California.

Danielle Mauragis Danielle Mauragis, CVT, is a radiology technician at University of Florida College of Veterinary Medicine, where she teaches diagnostic imaging. She coauthored the Handbook of Radiographic Positioning for Veterinary Technicians and received the Florida Veterinary Medical Association’s 2011 Certified Veterinary Technician of the Year award.

The internal iliac (formerly “hypogastric”) and sacral lymph nodes are found between the origin of the external and internal iliac arteries and alongside the median sacral artery, respectively. These lymph nodes receive afferent lymphatics from the rectum, pelvic canal, anal glands, and perineal region. Although these nodes are not routinely identified, this area should be evaluated as metastases from tumors in these regions do occur with enlargement of these specific lymph nodes, and the internal iliac lymph nodes may then be appreciated.18,19 Unless severely enlarged, the sacral lymph nodes are typically not visible ultrasonographically due to their position in the pelvic canal. They are obscured by the shadow from the pubic bones.

Visceral Nodes The jejunal or mesenteric lymph nodes are the largest lymph nodes in the abdomen. They are located around the cranial mesenteric artery and vein in the right cranial to middle abdomen just to the right of the umbilicus (Figure 11). These lymph nodes are vermiform, cylindrical, and elongated and measure up to 0.5 cm thick and up to 3 to 4 cm long.20

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FIGURE 11. Mildly enlarged (10 mm) mesenteric lymph nodes (arrows) from a 4-month-old dog. This degree of mild lymphadenomegaly is normal in puppies.

Contrast ultrasonography has been described to better characterize lymph node enlargement patterns.21 The jejunal lymph nodes are usually reactive and enlarged in young dogs and cats up to 1 year of age (Figure 11).3,4,13 They can be heteroechoic with multiple peripheral hypoechoic nodules. The jejunal or mesenteric lymph nodes are commonly enlarged in inflammatory (eg, secondary to inflammatory bowel disease), infectious (eg, pythiosis), and neoplastic (eg, metastatic disease from adenocarcinoma or involvement in multicentric round cell neoplasia; Figures 12 and 13) disorders of the gastrointestinal tract.

The appearance of the cisterni chyli has been reported as an anechoic tubular structure, without detectable flow, at the right dorsolateral aspect of the aorta at the level of the cranial mesenteric artery. The shape and size of the cisterna chyli in an individual dog can vary during the same ultrasound examination and between different examinations.22

SUMMARY As in all cases of abdominal disease, increases or decreases in overall echogenicity are subjective, and sonographers must be familiar with how the peritoneal and retroperitoneal spaces and abdominal lymph nodes appear in normal dogs and cats when scanned with their machines. Severe enlargement of abdominal lymph nodes is usually an indicator of neoplasia (multicentric or metastatic); however, mild to moderate enlargement can indicate either neoplasia or reactive lymphadenopathy secondary to inflammation or infection.

To see the references for this article, please visit tvpjournal.com.

IMAGING ESSENTIALS

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FIGURE 12. Enlarged, oval, hypoechoic lymph nodes from 2 dogs with abdominal pathology. (A) Internal iliac lymph node (arrow) in a dog with lymphoma. (B) Mesenteric lymph node (arrows) in a dog with histiocytic sarcoma.

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FIGURE 13. (A) Enlarged mesenteric (jejunal) lymph nodes in a cat with large B-cell lymphoma. (B) Enlarged mesenteric lymph nodes with surrounding echogenic mesentery from a dog with duodenal and gastric masses secondary to a Pythium infection.

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CLINICAL INSIGHTS

What to Do With Lumps and Bumps Sue Ettinger, DVM, DACVIM (Oncology) VCA Animal Specialty & Emergency Center, Wappingers Falls, New York Shutterstock.com/Edward Acker

Welcome to Clinical Insights — a series of articles by Dr. Sue Ettinger, head of the Oncology Department at Animal Specialty & Emergency Center in Wappinger Falls, New York.

Dr. Ettinger’s mission is to promote awareness and education about cancer in pets. In these articles, she will combine her expertise in oncology with her experiences in practice to detail how clinicians can better care for cancer patients.

I’ll be honest, it’s easy to get complacent. My oncology nurse had a pit bull, Smokey, whose medical record contained aspiration results from more than 10 lipomas. I performed and documented all those aspirations. When we found another mass, we waited to get an aspirate, because—based on appearance and Smokey’s history—we assumed it was benign. When we finally tested it, the 7-cm mass over his flank turned out to be a low-grade soft tissue sarcoma.

LET’S GET SPECIFIC When a pet presents with a dermal or subcutaneous mass, the owner is often told, “Keep an eye on it.”

But what does that mean? Keep an eye on it for how long? How much should a mass grow before it is investigated? As a cancer specialist, I hear all too often that a mass does not “look” or “feel” malignant. The truth is that even an experienced cancer specialist (like me) cannot look at or feel a mass and know what it is.

The current recommendations for working up a mass include the same generalities our clients hear: “Recommend if a mass is changing in size or appearance, or bothering the patient.”1 Again, what does this mean? What changes are clinically significant—any?

All? What constitutes patient “bother”? These kinds of measures are not enough. A standard of care is needed for skin and subcutaneous masses in dogs and cats.

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Although Smokey’s tumor was successfully removed with wide and clean margins, it highlighted for me the need for more definitive guidelines to promote early cancer detection (Box 1).

It is well documented that cytologic and histologic evaluations are important diagnostic tools in veterinary oncology and that obtaining a preliminary diagnosis optimizes treatment planning. The 2016 AAHA Oncology Guidelines for Dogs and Cats summarize the tools used for diagnosis, staging, and treatment of common tumor types.2 It is also recommended to evaluate masses that are growing, changing in appearance, or irritating to the patient.1 However, at this time, no specific guidelines exist for determining when to aspirate, biopsy, or monitor canine and feline skin and subcutaneous masses.

CLINICAL INSIGHTS

Without guidelines to increase both public and professional awareness, superficial masses may be monitored for too long. Allowing a tumor to grow can turn what might have been a simple surgical removal into a much more complicated one. Surgical excision of larger masses may result in less than adequate surgical margins (narrow or incomplete), leading to recurrence and additional costly therapy (more aggressive local surgery, radiation therapy, and/or chemotherapy).

Even worse, the tumor may become too big or advanced to be removed or treated at all. I see this all the time. These are often the most frustrating and heartbreaking cases. In veterinary medicine, most skin and subcutaneous tumors can be cured with surgery alone if diagnosed early when they are small.

I’ve learned three things from Smokey and from my time as a cancer specialist:

BOX 1. See Something, Do Something.

Why Wait? Aspirate.® I developed the guidelines I recommend in this article with the input of fellow specialists and VCA Animal Hospitals, Inc, as the See Something, Do Something. Why Wait? Aspirate® campaign. I hope they will increase client awareness, promote early cancer detection and diagnosis, and encourage early surgical intervention. We all must do better. We must find tumors earlier when they are small, and we must aspirate them sooner.

2. Know What a Mass Is Before You Remove It

1. Be proactive with lumps and bumps.

Diagnosis of many skin and subcutaneous masses can be achieved with fine needle aspiration (FNA) and cytology.1

2. Know what a mass is before you remove it.

Aspiration and Cytology

3. Make the first surgery the only surgery.

1. Be Proactive With Lumps and Bumps See something: If a dog or cat has a mass that is the size of a pea (1 cm) and has been there 1 month, Do something: Aspirate or biopsy, and treat appropriately!

Obtaining a definitive diagnosis with cytology or biopsy early and before excision will lead to improved patient outcomes for superficial masses. When smaller, superficial tumors are detected early, surgery is likely curative, especially for benign lesions and tumors that are only locally invasive with a low probability of metastasis. If a tumor is removed with complete surgical margins, the prognosis is often good with no additional treatments needed.

Although the See Something, Do Something guidelines specify a 1-cm mass, smaller masses may also be aspirated or biopsied. However, they should not be allowed to grow larger than 1 cm without investigation. Practitioners should measure and document the size of the initial mass for comparison to see growth, and educate clients about the “pea” size requirement to encourage them to have masses evaluated.

FNA and cytology provide a diagnosis for many dermal and subcutaneous masses, especially those that that exfoliate well. FNA is useful to distinguish neoplasia from inflammation and benign masses, including lipomas and sebaceous adenomas. Cellular morphology may also allow the determination of benign or malignant phenotype. For malignant tumors, cytology provides information that assists in formulating diagnostic and treatment plans.

Advantages of cytology include minimally invasive approach, low risk, low cost, and results that are available more quickly than biopsy results. The disadvantages are that results may be nondiagnostic or equivocal because of a small number of cells in the sample, poor exfoliation of the cells, or poor sample quality. In these cases, histopathologic confirmation may be required for definitive diagnosis.3 FNA may be accomplished using one of two techniques: aspiration or fenestration. During aspiration, the needle and syringe are attached, and vacuum is maintained. In fenestration, the needle alone is inserted into the mass percutaneously.

Fenestration is done without aspiration, often yields more cellular material, and causes less hemorrhage.3 The See Something, Do Something. Why Wait? Aspirate. program was jointly developed by Dr.Sue Ettinger and VCA Animal Hospitals, Inc. © 2017 See Something, Do Something. Why Wait? Aspirate. All rights reserved.

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I personally prefer and start with fenestration as I find it easier and consistently get diagnostic samples.

Aspiration is more useful for fluid-filled masses.

Unless the sample is composed exclusively of fat, clear cystic fluid, or acellular debris, it should be submitted to a trained cytopathologist. When in doubt, send it out. Including an adequate history helps the pathologist make an accurate diagnosis.

Biopsy If cytology is nondiagnostic, a pretreatment biopsy is recommended before complete tumor removal. This biopsy will help determine the optimal treatment plan.

A practical recommendation in these cases is if the lesion fits in an 8-mm biopsy punch, punch it out.

If the mass is larger than an 8-mm biopsy punch, an incisional biopsy (wedge, Tru-cut, punch) is required for diagnostic confirmation before tumor removal.

Staging diagnostics are also often indicated before curativeintent surgery. Consultation with a veterinary oncologist is recommended to help in these diagnostic decisions.

3. Make the First Surgery the Only Surgery It is tempting to remove a mass right away, and owners often say they want it removed as soon as possible.

An excisional biopsy establishes a diagnosis and removes the tumor at the same time. However, this approach is not recommended for undiagnosed skin and superficial masses because surgical approaches

vary with tumor type. For benign masses, marginal excision may be adequate for long-term control. In contrast, malignant tumors often require 2 to 3 cm margins.1,4–6 When an excisional biopsy (or debulking surgery) leads to incomplete margins for malignant tumors, more treatment, more morbidity, and more expense ensue. Thus, removing the mass entirely is not recommended without a cellular diagnosis before definitive excision. Research confirms that the first surgery is the best chance for a cure.2

WHAT WILL WE FIND? Primary skin and subcutaneous tumors are common in dogs and cats. While the overall incidence is difficult to determine, approximately 25% to 43% of submitted canine and feline biopsy samples are of the skin. Of submitted samples, 20% to 40% are reported to be malignant.7 The most common malignant skin tumors in dogs are mast cell tumors, soft tissue sarcomas, and squamous cell carcinomas (Table 1). The most common benign canine skin and subcutaneous benign tumors include lipomas, histiocytomas, and perianal gland adenomas.7 In cats, the most common superficial tumors are basal cell tumors, mast cell tumors, squamous cell carcinomas, and fibrosarcomas. These 4 tumor types make up about 70% of all skin tumors in cats.

Sebaceous gland adenomas are much less common.

If basal cell tumors are excluded, the percentage of malignant skin tumors in cats is higher than in dogs, with studies reporting 70% to 80%.7

TABLE 1 Most Common Skin Tumors in Dogs and Cats1,7 DOGS

CATS

MALIGNANT

BENIGN

MALIGNANT

BENIGN

Mast cell tumors: 10%–17%

Lipomas: 8%

Hemangiosarcoma 23%

Mast cell tumors: 13%–21%

Soft tissue sarcomas:

Histiocytomas: 8%–12%

Melanomaa 1%–2%

Basal cell tumors: 15%–26%

Perianal gland adenomas: 8%–12%

Squamous cell carcinomas: 10%–15%

Sebaceous gland adenomas: 2%–4%

Sebaceous gland adenomas/ hyperplasia: 4%–6%

Fibrosarcomas: 15%–17%

Apocrine adenoma 4%–5%

Fibrosarcomas: 2%–6% Malignant nerve sheath tumors: 4%–7% Squamous cell carcinomas: 2%–6%

Trichoepitheliomas: 4% Papillomas: 3% Basal cell tumors: 4%–5% Melanomas 4%–6% Hemangioma 4%

The biologic behavior of melanoma in cats is less predictable than in dogs.

a

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CLINICAL INSIGHTS

Lipoma 3%

CLINICAL INSIGHTS

Sue Ettinger Sue Ettinger, DVM, DACVIM (Oncology), is head of the Oncology Department at Animal Specialty & Emergency Center in Wappinger Falls, in the Hudson Valley of New York. Also known as Dr. Sue Cancer Vet, she is the coauthor of the second edition of The Dog Cancer Survival Guide, cohost of the podcast The Pet Cancer Vet (radiopetlady.com), and an international speaker. Dr. Ettinger developed See Something, Do Something, Why Wait? Aspirate—a cancer awareness initiative for skin and superficial tumors in dogs and cats. She received her DVM from Cornell University and completed a medical oncology residency at The Animal Medical Center in New York City. Dr. Ettinger can be found on Facebook (facebook.com/DrSueCancerVet) and Twitter (@DrSueCancerVet).

VET

SUMMARY Visual monitoring of superficial masses is not enough. Cancer is a cellular diagnosis. It is always recommended to evaluate masses that are growing, changing in appearance, or irritating to the patient, but these guidelines are not enough. All skin and subcutaneous masses that are >1 cm and have been present for 1 month should be aspirated for cytologic evaluation.

Biopsy is indicated if cytology does not provide a diagnosis.

Veterinary professionals and pet owners all must be proactive to advocate for early cancer detection. If tumors are detected and removed earlier—when they are small and with clean margins—the prognosis is often good and the patient may not require additional therapy. See something, do something!

References 1.

Northrup N, Geiger T. Tumors of the skin, subcutis and other soft tissues. In: Henry C, Higginbotham ML, eds. Cancer Management in Small Animal Practice.

Saunders; 2010: 299-313.

NEW! Animal Medical Kits available to sell to your customers for a total clinic approach. Sell

2. Biller B, Berg J, Garrett L, et al. 2016 AAHA Oncology Guidelines for Dogs and Cats. Available at: aaha.org/graphics/original/professional/resources/ guidelines/2016_aaha_oncology_guidelines_for_dogs_and_cats.pdf. Accessed April 2017.

3. Henry CJ, Pope ER. Methods of tumor diagnosis: fine needle aspiration and biopsy techniques. In: Henry C, Higginbotham ML, eds. Cancer Management in Small Animal Practice. Saunders; 2010: 41-58.

4. Selting KA. Soft tissue sarcomas. In: Henry C, Higginbotham ML, eds. Cancer Management in Small Animal Practice. Saunders; 2010: 321-324.

5. London CA, Thamm DH. Mast cell tumors. In: Withrow SJ, Vail DM, Page R, eds.

Small Animal Clinical Oncology. 5th ed. St. Louis, MO: Elsevier Saunders; 2013: 333-355.

6. Liptak JM, Forrest LJ. Soft tissue sarcomas. In: In: Withrow SJ, Vail DM, Page R, eds. Small Animal Clinical Oncology. 5th ed. St. Louis, MO: Elsevier Saunders; 2013: 356-380.

7. Hauck ML. Tumors of the skin and subcutaneous tissues. In: In: Withrow SJ, Vail DM, Page R, eds. Small Animal Clinical Oncology. 5th ed. St. Louis, MO: Elsevier Saunders; 2013: 305-320.

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PRACTICAL TOXICOLOGY

Ethanol Toxicosis: A Review Tina Wismer, DVM, DABVT, DABT ASPCA Animal Poison Control Center, Urbana, Illinois shutterstock.com/Nicki Mannix

Welcome to Practical Toxicology, brought to you in partnership between Today’s Veterinary Practice and the ASPCA Animal Poison Control Center (APCC) (aspcapro.org/poison). This column provides practical clinical information about diagnosing and treating pets that have been exposed to potentially harmful substances.

The APCC: •P rovides 24-hour diagnostic and treatment recommendations by specially trained veterinary toxicologists •P rotects and improves animal lives through toxicology education, consulting services, and case data review •D eveloped and maintains AnTox, an animal toxicology database system that identifies and characterizes toxic effects of substances in animals •W orks closely with human poison control centers to provide animal poisoning information •O ffers extensive veterinary toxicology consulting to organizations in industry, government, and agriculture.

If treating a patient that requires emergency care for poisoning, call the APCC at 888-426-4435.

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PRACTICAL TOXICOLOGY

Although we mostly think of ethanol (ethyl alcohol) as the alcohol used in beverages, it is also found in other substances: liquid medications, cosmetics, hand sanitizers, perfumes, colognes, mouthwashes, food flavorings (eg, vanilla extract), alcohol-filled chocolates, and fermenting yeast bread dough. Ethanol is produced from fermentation of sugar, cellulose, or starch, which is why ingestion of raw yeast dough causes intoxication.1 Although ethanol is used to treat ethylene glycol toxicosis, ingestion of ethanol can be dangerous. Most animal exposures to ethanol result from beverages being left unattended. Alcoholic drinks made with milk or cream are especially attractive to pets.

ETHANOL ABSORPTION Ethanol is a central nervous system (CNS) depressant.

It enhances the inhibitory effects of gammaaminobutyric acid (GABA) at the GABA-A receptor and competitively inhibits the binding of glycine at the N-methyl-d-aspartate receptor (it disrupts excitatory glutaminergic neurotransmission).2 Ethanol also stimulates release of other inhibitory neurotransmitters, such as dopamine and serotonin.

Ethanol is absorbed rapidly and completely from the stomach, small intestine, and colon. In humans, 80%

PRACTICAL TOXICOLOGY

to 90% is absorbed within 30 to 60 minutes.3 Ethanol can also be absorbed dermally, especially if the skin is not intact.2 Peak plasma levels occur 30 minutes to 2 hours after ingestion but can be delayed after larger doses or in the presence of food.3 Although the time to reach peak plasma levels in these situations is increased, there is little difference in the amount absorbed.4 Most ingested ethanol (95%) is metabolized in the liver by alcohol dehydrogenase to acetaldehyde and then to acetic acid.3 About 5% to 10% is excreted unchanged in the breath, urine, sweat, and feces.3,5,6

Hypothermia may result from multiple mechanisms.

Peripheral vasodilation, CNS depression, ethanol interference with the thermoregulator mechanism, and/or impaired behavioral responses to a cold environment all lead to a lowered body temperature.3

The elimination half-life is not meaningful because it is affected by saturation of the metabolizing enzymes.5 At lower concentrations, the elimination rate may be nonlinear (first-order reaction), but it becomes linear (zero-order reaction) at high concentrations when all the available alcohol dehydrogenase is occupied.5 In the average human adult, the blood level of ethanol decreases by 15 to 20 mg/dL per hour.6 In animals, the onset of action is typically within 1 hour of exposure; most animals recover within 12 to 24 hours.7–9

• In cases of dermal exposure, bathe the animal to reduce both dermal absorption and ingestion resulting from grooming behaviors.

MANAGEMENT • Induce emesis only in asymptomatic animals.

Activated charcoal is not indicated because it binds poorly to ethanol.15 In addition, because ethanol toxicosis is characterized by vomiting, the risk for charcoal aspiration is high.

• Monitor heart rate and rhythm, blood pressure, and body temperature. Monitor for acidosis and calculate anion gap if possible. The normal anion gap for dogs and cats is 10 to 15 mEq/L. Values greater than 25 mEq/L are considered acidotic.16 Although there TABLE 1 Ethanol Concentrations in Alcoholic Beverages and Other Household Products 5,10

The amount of ethanol needed to cause intoxication varies depending on its concentration in the substance ingested (Table 1). The published oral lethal dose in dogs is 5.5 to 7.9 g/kg of 100% ethanol.11 One milliliter of ethanol is equal to 0.789 g. Kammerer et al reported a case of lethal ethanol toxicosis in a dog caused by the massive ingestion of rotten apples.12

% ETHANOL BY VOLUME

Light beer

5–7

2.5–3.5

Beer

8–12

4–6

Ale

10–16

5–8

20–40

10–20

Wine

CLINICAL SIGNS

Mouthwash Amaretto

The most common clinical signs of ethanol toxicosis are ataxia, lethargy, vomiting, and recumbency. In more severe cases, hypothermia, disorientation, vocalization, hypotension, tremors, tachycardia, acidosis, diarrhea, respiratory depression, coma, seizures, and death may occur.4 Alcohol is directly irritating to the stomach and causes vomiting. High ethanol blood levels also stimulate emesis. The concern with vomiting during intoxication is that at high blood ethanol concentrations, the muscles that control the epiglottis become slow to react or even paralyzed.

This increases the risk for aspiration.13 Ethanol intoxication reduces peripheral oxygen delivery and metabolism and causes mitochondrial oxidative dysfunction, potentially resulting in shock or hypoxia in an acutely intoxicated patient.14

PROOFa

SUBSTANCE

14–27 34–56

Aftershave Schnapps

17–28 19–90

40–100

20–50

Coffee liqueurs

42–53

21–26.5

Brandy

70–80

35–40

Bourbon

80–90

40–45

Rum

80–82

40–41

Cognac

80–82

40–41

Vodka

80–82

40–41

Whiskey

80–90

40–45

Tequila

80–92

40–46

Gin

80–94

40–47

Cologne/perfume

50

Hand sanitizers

60–95

For alcoholic beverages, the proof is double the percentage of alcohol present. a

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are no data on how often acidosis occurs in pets, about 45% of intoxicated humans become acidotic.17 • Monitor for hypoglycemia. If dietary and hepatic (glycogenolysis) sources of glucose are exhausted, hypoglycemia may result. During the oxidation of ethanol, the ratio between oxidized and reduced forms of nicotinamide adenine dinucleotide increases, which increases the conversion of pyruvate to lactate. This leads to a lack of the key intermediate in gluconeogenesis, pyruvate, and hypoglycemia ensues.18 Hypoglycemia, which can result in seizures and coma, is a serious complication of acute alcoholic intoxication.10 Dextrose may need to be added to IV fluids.

• IV fluids do not accelerate ethanol clearance in intoxicated patients but should be started for supportive purposes.19 Use isotonic solutions. Sodium bicarbonate (0.5 × kg body weight × base deficit = deficit in mEq) can be added to combat metabolic acidosis. Give half the sodium bicarbonate dose over 3 to 4 hours.20 • Treat any arrhythmias symptomatically (atropine for bradycardia, lidocaine for ventricular premature contractions). Control seizures not related to hypoglycemia with diazepam. If the animal is comatose, pass an endotracheal tube and position the patient to prevent aspiration. In cases of severe intoxication, monitor oxygen saturation and be prepared to mechanically support the animal’s breathing. Yohimbine (0.11 mg/kg IV), atipamezole (100 mcg/kg IV), or naloxone (0.1 mg/kg IV)

can be tried to reverse severe CNS depression or coma.20 This reversal effect does not appear to be predictable or consistent in animals.21 Animals that are mildly affected may be monitored at home. Patients with significant CNS depression, those requiring airway protection or ventilatory support, and those with seizures, acid-base disturbances, or hypoglycemia should be admitted for monitoring and supportive care. In severe cases, hemodialysis may be considered. Keno and Langston reported using hemodialysis in a dog with rapid clinical recovery.22 Hemodialysis can eliminate ethanol approximately 3 to 4 times more rapidly than liver metabolism alone.

Although ethanol levels may be determined from blood, serum, plasma, and urine, they are seldom measured in pets.23 In most cases, such measurements need to be performed at a human hospital. In humans, blood ethanol concentrations between 150 and 300 mg/dL (32.6 to 65.2 mmol/L) generally cause obvious signs and symptoms. Death is usually associated with blood ethanol levels >400 mg/dL (86.8 mmol/L).3 In the case report by Kammerer et al, the dog that ingested rotten apples exhibited vomiting, ataxia, tremors, and dehydration and died 48 hours later with an alcoholemia of 300 mg/dL.12 If the blood ethanol level cannot be measured, serum or plasma osmolality may be used to estimate it, using the following formula24: Blood ethanol level [g/L] = Osmolal gap/27

DIFFERENTIAL DIAGNOSIS

Tina Wismer Tina Wismer, DVM, DABVT, DABT, is responsible for overseeing medical recommendations made by the veterinary staff at ASPCA Animal Poison Control Center (APCC). She is also highly involved in lecturing, making media appearances, and writing, and she coordinates the APCC’s extern program. Dr. Wismer earned her undergraduate degree from Ohio’s University of Findlay and received her DVM from Purdue University. Her first job was in a small animal practice in Michigan. She then worked for an emergency practice in South Bend, Indiana, before joining the APCC. Dr. Wismer has written several peer-reviewed toxicology articles and book chapters. She is an adjunct instructor at the University of Illinois, previously a visiting professor at St. Matthews University (Cayman), a consultant for VIN (Veterinary Information Network), and a Master Gardener.

Most ethanol intoxications are unmistakable because of the odor of alcohol on the pet’s breath. However, other toxic differentials for intoxicated patients include salicylates, marijuana, toluene, ethylene glycol, methanol, isopropanol, benzodiazepines, barbiturates, opiates, and gamma-hydroxybutyric acid.7–9 Nontoxic differentials include lactic acidosis, uremia, diabetic ketoacidosis, cardiovascular accident, hypoglycemia, and hypoxia.7–9

PROGNOSIS In most cases of ethanol ingestion, the prognosis is good.

Cases complicated by aspiration of gastric contents, presence of other ingested material, or preexisting disease have a more guarded prognosis. Intoxicated animals are also predisposed to traumatic injuries.

To see the references for this article, please visit tvpjournal.com.

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PRACTICAL TOXICOLOGY

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