Compendium | February 2009 by davidpsu

VOLUME 31 NUMBER 2 FEBRUARY 2009

Compendium CompendiumVet.com | Peer Reviewed | Listed in MEDLINE

6 CE Contact Hours

Vol 31(2) February 2009

CONTI N U I NG EDUCATION FOR VETERI NARIANS ®

COMPENDIUM CONTINUING EDUCATION FOR VETERINARIANS® Refereed Peer Review

Laparoscopic Gastropexy FREE

PAGES 49–96

Oral Examination O of Cats and Dogs o

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February 2009 Vol 31(2) CompendiumVet.com | Peer Reviewed | Listed in MEDLINE

EXECUTIVE EDITOR Tracey Giannouris, MA 800-426-9119, ext 52447 | tgiannouris@vetlearn.com MANAGING EDITOR Kirk McKay 800-426-9119, ext 52434 | kmckay@vetlearn.com Subscription inquiries: 800-426-9119, option 2. Subscription rate: $79 for 1 year; $143 for 2 years; $217 for 3 years. Canadian and Mexican subscriptions (surface mail): $95 for 1 year; $169 for 2 years; $270 for 3 years. Foreign subscriptions (surface mail): $175 for 1 year; $275 for 2 years; $425 for 3 years. Payments by check must be in U.S. funds drawn on a U.S. branch of a U.S. bank only; credit cards are also accepted. Change of Address: Please notify the Circulation Department 45 days before the change is to be effective. Send your new address and enclose an address label from a recent issue. Selected back issues are available for $15 (United States and Canada) and $17 (foreign) each (plus postage). Indexing: Compendium: Continuing Education for Veterinarians® is included in the international indexing coverage of Current Contents/ Agriculture, Biology and Environmental Sciences (ISI); SciSearch (ISI); Research Alert (ISI); Focus On: Veterinary Science and Medicine (ISI); Index Veterinarius (CAB International, CAB Abstracts, CAB Health); and Agricola (Library of Congress). Article retrieval systems include The Genuine Article (ISI), The Copyright Clearance Center, Inc., University Microfilms International, and Source One (Knight-Ridder Information, Inc.). Yearly author and subject indexes for Compendium are published each December.

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Published monthly by Veterinary Learning Systems, a division of MediMedia, 780 Township Line Road, Yardley, PA 19067. Copyright © 2009 Veterinary Learning Systems. All rights reserved. Printed in the USA. No part of this issue may be reproduced in any form by any means without prior written permission of the publisher. Printed on acid-free paper, effective with volume 29, issue 5, 2007. Periodicals postage paid at Morrisville, PA, and at additional mailing offices. Postmaster: Send address changes to Compendium: Continuing Education for Veterinarians®, 780 Township Line Road, Yardley, PA 19067. Canada Post international publications mail product (Canadian distribution) sales agreement no. 40014103. Return undeliverable Canadian addresses to MediMedia, PO Box 7224, Windsor, ON N9A 0B1. Printed in USA.

Compendium: Continuing Education for Veterinarians® (ISSN 1940-8307)

EXECUTIVE OFFICER Derrick Kraemer, President CUSTOMER SERVICE 800-426-9119, option 2 | info.vls@medimedia.com CompendiumVet.com

February 2009 Vol 31(2) CompendiumVet.com | Peer Reviewed | Listed in MEDLINE

EDITORIAL BOARD Anesthesia Nora S. Matthews, DVM, DACVA Texas A&M University

Internal Medicine Dana G. Allen, DVM, MSc, DACVIM Ontario Veterinary College

Cardiology Bruce Keene, DVM, MSc, DACVIM North Carolina State University

Internal Medicine and Emergency/ Critical Care Alison R. Gaynor, DVM, DACVIM (Internal Medicine), DACVECC North Grafton, Massachusetts

Clinical Chemistry, Hematology, and Urinalysis Betsy Welles, DVM, PhD, DACVP Auburn University

EDITOR IN CHIEF Douglass K. Macintire, DVM, MS, DACVIM, DACVECC

Department of Clinical Sciences College of Veterinary Medicine Auburn University, AL 36849

Dentistry Gary B. Beard, DVM, DAVDC Auburn University R. Michael Peak, DVM, DAVDC The Pet Dentist—Tampa Bay Veterinary Dentistry Largo, Florida Emergency/Critical Care and Respiratory Medicine Lesley King, MVB, MRCVS, DACVECC, DACVIM University of Pennsylvania Endocrinology and Metabolic Disorders Marie E. Kerl, DVM, ACVIM, ACVECC University of Missouri-Columbia

EXECUTIVE ADVISORY BOARD MEMBERS Behavior Sharon L. Crowell-Davis, DVM, PhD, DACVB The University of Georgia Dermatology Craig E. Grifﬁn, DVM, DACVD Animal Dermatology Clinic San Diego, California Wayne S. Rosenkrantz, DVM, DACVD Animal Dermatology Clinic Tustin, California Nutrition Kathryn E. Michel, DVM, MS, DACVN University of Pennsylvania Surgery Elizabeth M. Hardie, DVM, PhD, DACVS North Carolina State University

CompendiumVet.com m

Epidemiology Philip H. Kass, DVM, MPVM, MS, PhD, DACVPM University of California, Davis Exotics Avian Thomas N. Tully, Jr, DVM, MS, DABVP (Avian), ECAMS Louisiana State University Reptiles Douglas R. Mader, MS, DVM, DABVP (DC) Marathon Veterinary Hospital Marathon, Florida Small Mammals Karen Rosenthal, DVM, MS, DABVP (Avian) University of Pennsylvania Feline Medicine Michael R. Lappin, DVM, PhD, DACVIM (Internal Medicine) Colorado State University Margie Scherk, DVM, DABVP (Feline Medicine) Cats Only Veterinary Clinic Vancouver, British Columbia Gastroenterology Debra L. Zoran, DVM, MS, PhD, DACVIM (Internal Medicine) Texas A&M University Infectious Disease Derek P. Burney, PhD, DVM Gulf Coast Veterinary Specialists Houston, Texas

Nephrology Catherine E. Langston, DVM, ACVIM Animal Medical Center New York, New York Neurology Curtis W. Dewey, DVM, MS, DACVIM (Neurology), DACVS Cornell University Hospital for Animals Oncology Ann E. Hohenhaus, DVM, DACVIM (Oncology and Internal Medicine) Animal Medical Center New York, New York Gregory K. Ogilvie, DVM, DACVIM (Internal Medicine and Oncology) CVS Angel Care Cancer Center and Special Care Foundation for Companion Animals San Marcos, California Ophthalmology David A. Wilkie, DVM, MS, DACVO The Ohio State University Parasitology Byron L. Blagburn, MS, PhD Auburn University David S. Lindsay, PhD Virginia Polytechnic Institute and State University Pharmacology Katrina L. Mealey, DVM, PhD, DACVIM, DACVCP Washington State University Rehabilitation and Physical Therapy Darryl Millis, MS, DVM, DACVS University of Tennessee Surgery Philipp Mayhew, BVM&S, MRCVS, DACVS Columbia River Veterinary Specialists Vancouver, Washington C. Thomas Nelson, DVM Animal Medical Center Anniston, Alabama Surgery and Orthopedics Ron Montgomery, DVM, MS, DACVS Auburn University Toxicology Tina Wismer, DVM, DABVT, DABT ASPCA National Animal Poison Control Center Urbana, Illinois

AMERICAN BOARD OF VETERINARY PRACTITIONERS (ABVP) REVIEW BOARD Kurt Blaicher, DVM, DABVP (Canine/Feline) Plainﬁeld Animal Hospital Plainﬁeld, New Jersey Canine and Feline Medicine Eric Chafetz, DVM, DABVP (Canine/Feline) Vienna Animal Hospital Vienna, Virginia Canine and Feline Medicine Henry E. Childers, DVM, DABVP (Canine/Feline) Cranston Animal Hospital Cranston, Rhode Island Canine and Feline Medicine David E. Harling, DVM, DABVP (Canine/Feline), DACVO Reidsville Veterinary Hospital Reidsville, North Carolina Canine and Feline Medicine, Ophthalmology Jeffrey Katuna, DVM, DABVP Wellesley-Natick Veterinary Hospital Natick, Massachusetts Canine and Feline Medicine Robert J. Neunzig, DVM, DABVP (Canine/Feline) The Pet Hospital Bessemer City, North Carolina Canine and Feline Medicine

Compendium is a refereed journal. Articles published herein have been reviewed by at least two academic experts on the respective topic and by an ABVP practitioner. Any statements, claims, or product endorsements made in Compendium are solely the opinions of our authors and advertisers and do not necessarily reﬂect the views of the Publisher or Editorial Board.

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E Each CE article is accredited for 3 contact hours by A Auburn University College of Veterinary Medicine.

February 2009 Vol 31(2)

Features 68

CompendiumVet.com | Peer Reviewed | Listed in MEDLINE

Understanding Behavior Behavior Assessment: Completing the Examination

Surgical Views 58 Laparoscopic-Assisted and Laparoscopic Prophylactic Gastropexy: Indications and Techniques

❯❯ Sharon L. Crowell-Davis The third article in this series on behavior patient assessment discusses the beneﬁts of direct patient observation in the ofﬁce and at home.

❯❯ Jeffrey J. Runge, Philipp Mayhew,

and Clarence A. Rawlings

Oral Examination of Cats and Dogs

FREE

CE ❯❯ Dale Kressin This well-illustrated guide to the complete t oral examination can help general practitioners become familiar with the basics of normal ﬁndings versus pathology.

Prophylactic gastropexy can substantially reduce the mortality associated with gastric dilatation–volvulus in certain breeds of dogs. When this surgery is performed using laparoscopic techniques, postoperative pain is decreased. Videos of some of these techniques are available at CompendiumVet.com.

Canine oral examination PAGE 77

Obstructive Lesions and Traumatic Injuries j of the Canine and Feline Tracheas FREE

❯❯ Wesley Roach and D. J. Krahwinkel, Jr. CE The authors review the anatomy and physiology of the canine and feline tracheas and the diagnosis and treatment of tracheal injuries.

Departments Ian Cummings Photography

54 CompendiumVet.com 55 Guest Editorial: Some People Use Data Like Drunks Use Lampposts ❯❯ C. A. Tony Bufﬁngton

66 Reading Room: Small Animal Surgery, 3rd ed 94 Market Showcase 95 Classiﬁed Advertising 95 Index to Advertisers

Correction In the caption of Figure 4 of the December 2008 article “Feline Diabetes Mellitus: Diagnosis, Treatment, and Monitoring,” the scalpel handle shown in the image was incorrectly identiﬁed as a forceps.

Compendium: Continuing Education for Veterinarians®

On the Cover In the article beginning on page 58, Drs. Mayhew, Runge, and Rawlings (left to right, above) outline various laparoscopic techniques for the prevention of gastric dilatation–volvulus in dogs. (Photo taken by Ian Cummings Photography, courtesy of the American College of Veterinary Surgeons (ACVS) at the 2008 ACVS Veterinary Symposium, San Diego, CA.)

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What makes this even harder to take

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HEARTGARDÂŽ is well tolerated. All dogs should be tested for heartworm infection before starting a preventive program. Following the use of HEARTGARD, digestive and neurological side effects have rarely been reported. For more information, please visit www.HEARTGARD.com.

See Page 54 for Product Information Summary

February 2009

WEB EXCLUSIVES

Vol 31(2)

CHEWABLES CAUTION: Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: For use in dogs to prevent canine heartworm disease by eliminating the tissue stage of heartworm larvae (Dirofilaria immitis) for a month (30 days) after infection and for the treatment and control of ascarids (Toxocara canis, Toxascaris leonina) and hookworms (Ancylostoma caninum, Uncinaria stenocephala, Ancylostoma braziliense). DOSAGE: HEARTGARD® Plus (ivermectin/pyrantel) Chewables should be administered orally at monthly intervals at the recommended minimum dose level of 6 mcg of ivermectin per kilogram (2.72 mcg/lb) and 5 mg of pyrantel (as pamoate salt) per kg (2.27 mg/lb) of body weight. The recommended dosing schedule for prevention of canine heartworm disease and for the treatment and control of ascarids and hookworms is as follows: Dog Chewables Ivermectin Pyrantel Weight Per Month Content Content Up to 25 26 - 50 51 - 100

1 1 1

68 mcg 136 mcg 272 mcg

57 mg 114 mg 227 mg

Color Coding 0n Foil-Backing and Carton Blue Green Brown

HEARTGARD Plus is recommended for dogs 6 weeks of age and older. For dogs over 100 lb use the appropriate combination of these chewables. ADMINISTRATION: Remove only one chewable at a time from the foil-backed blister card. Return the card with the remaining chewables to its box to protect the product from light. Because most dogs find HEARTGARD Plus palatable, the product can be offered to the dog by hand. Alternatively, it may be added intact to a small amount of dog food.The chewable should be administered in a manner that encourages the dog to chew, rather than to swallow without chewing. Chewables may be broken into pieces and fed to dogs that normally swallow treats whole. Care should be taken that the dog consumes the complete dose, and treated animals should be observed for a few minutes after administration to ensure that part of the dose is not lost or rejected. If it is suspected that any of the dose has been lost, redosing is recommended. HEARTGARD Plus should be given at monthly intervals during the period of the year when mosquitoes (vectors), potentially carrying infective heartworm larvae, are active. The initial dose must be given within a month (30 days) after the dog’s first exposure to mosquitoes. The final dose must be given within a month (30 days) after the dog’s last exposure to mosquitoes. When replacing another heartworm preventive product in a heartworm disease prevention program, the first dose of HEARTGARD Plus must be given within a month (30 days) of the last dose of the former medication. If the interval between doses exceeds a month (30 days), the efficacy of ivermectin can be reduced. Therefore, for optimal performance, the chewable must be given once a month on or about the same day of the month. If treatment is delayed, whether by a few days or many, immediate treatment with HEARTGARD Plus and resumption of the recommended dosing regimen will minimize the opportunity for the development of adult heartworms. Monthly treatment with HEARTGARD Plus also provides effective treatment and control of ascarids (T. canis, T. leonina) and hookworms (A. caninum, U. stenocephala, A. braziliense). Clients should be advised of measures to be taken to prevent reinfection with intestinal parasites. EFFICACY: HEARTGARD Plus Chewables, given orally using the recommended dose and regimen, are effective against the tissue larval stage of D.immitis for a month (30 days) after infection and, as a result, prevent the development of the adult stage. HEARTGARD Plus Chewables are also effective against canine ascarids (T. canis, T. leonina) and hookworms (A. caninum, U. stenocephala, A. braziliense). ACCEPTABILITY: In acceptability and field trials, HEARTGARD Plus Chewables were shown to be an acceptable oral dosage form that was consumed at first offering by the majority of dogs. PRECAUTIONS: All dogs should be tested for existing heartworm infection before starting treatment with HEARTGARD Plus which is not effective against adult D. immitis. Infected dogs must be treated to remove adult heartworms and microfilariae before initiating a program with HEARTGARD Plus. While some microfilariae may be killed by the ivermectin in HEARTGARD Plus at the recommended dose level, HEARTGARD Plus is not effective for microfilariae clearance. A mild hypersensitivitytype reaction, presumably due to dead or dying microfilariae and particularly involving a transient diarrhea, has been observed in clinical trials with ivermectin alone after treatment of some dogs that have circulating microfilariae. Keep this and all drugs out of the reach of children. In case of ingestion by humans, clients should be advised to contact a physician immediately. Physicians may contact a Poison Control Center for advice concerning cases of ingestion by humans. Store at controlled room temperature of 68°F - 77°F (20°C - 25°C). Excursions between 59°F - 86°F (15°C - 30°C) are permitted. Protect product from light. ADVERSE REACTIONS: In clinical field trials with HEARTGARD Plus, vomiting or diarrhea within 24 hours of dosing was rarely observed (1.1% of administered doses). The following adverse reactions have been reported following the use of HEARTGARD: Depression/lethargy, vomiting, anorexia, diarrhea, mydriasis, ataxia, staggering, convulsions and hypersalivation. SAFETY: HEARTGARD Plus has been shown to be bioequivalent to HEARTGARD, with respect to the bioavailability of ivermectin. The dose regimens of HEARTGARD Plus and HEARTGARD are the same with regard to ivermectin (6 mcg/kg). Studies with ivermectin indicate that certain dogs of the Collie breed are more sensitive to the effects of ivermectin administered at elevated dose levels (more than 16 times the target use level) than dogs of other breeds. At elevated doses, sensitive dogs showed adverse reactions which included mydriasis, depression, ataxia, tremors, drooling, paresis, recumbency, excitability, stupor, coma and death. HEARTGARD demonstrated no signs of toxicity at 10 times the recommended dose (60 mcg/kg) in sensitive Collies. Results of these trials and bioequivalency studies, support the safety of HEARTGARD products in dogs, including Collies, when used as recommended. HEARTGARD Plus has shown a wide margin of safety at the recommended dose level in dogs, including pregnant or breeding bitches, stud dogs and puppies aged 6 or more weeks. In clinical trials, many commonly used flea collars, dips, shampoos, anthelmintics, antibiotics, vaccines and steroid preparations have been administered with HEARTGARD Plus in a heartworm disease prevention program. In one trial, where some pups had parvovirus, there was a marginal reduction in efficacy against intestinal nematodes, possibly due to a change in intestinal transit time. HOW SUPPLIED: HEARTGARD Plus is available in three dosage strengths (see DOSAGE section) for dogs of different weights. Each strength comes in convenient cartons of 6 and 12 chewables. For customer service, please contact Merial at 1-888-637-4251.

CE ARTICLES

❯❯ Anesthesia, Diagnostic Imaging, and Surgery of Fish ❯❯ E. Scott Weber, Chick Weisse, Tobias Schwarz, Charles Innis, and Alan M. Klide Anesthesia and diagnostic imaging modalities (e.g., radiology, ultrasonography, endoscopy) can be readily applied to ﬁsh and may help the clinician obtain valuable information. Despite some unique challenges, surgery can be performed in ﬁsh using basic surgical skills and principles and should be considered as a valid treatment option.

❯❯ Parasitology and Necropsy of Fish ❯❯ E. Scott Weber and Pam Govett Parasitic diseases are common in fish, and determining the cause of death in a fish is important for maintaining the health of other fish in the same environment. Necropsy is among the valuable diagnostic tools discussed in this article.

NEWS BITES

❯❯ Wireless Biopsy: A (Micro)gripping Tale Tiny, magnetically steered devices may someday be useful in obtaining biopsy samples.

❯❯ Pink Mice Prove the 20/80 Rule of Transmission Transmission of hantavirus in deer mice is linked to mouse size.

❯❯ The Beneﬁts of an “Animal House” Pets are good for college students…if they’re allowed in the dorm. VIDEO

❯❯ Laparoscopic Gastropexy After reading the article starting on page 58, watch three videos of various aspects of laparoscopic gastropexy.

FORMS

❯❯ Canine and Feline Oral Examination Charts These downloadable charts can help in documenting pathology during oral examinations in cats and dogs. E-NEWSLETTER ❯❯ COMPENDIUM EXTRA Our monthly e-newsletter provides Web Exclusive articles and news, as well as a preview of this month’s journal. Sign up at CompendiumVet.com.

Of dogs showing a preference in three studies conducted by independent investigators, dogs preferred HEARTGARD® (ivermectin) Chewables over INTERCEPTOR® (milbemycin oxime) FlavorTabs® by a margin of 37 to 1; data on file at Merial. 2 Data on file at Merial. 3 HEARTGARD Tablets Freedom of Information Summaries 1987.

®HEARTGARD and the Dog & Hand logo are registered trademarks of Merial. ®INTERCEPTOR is a registered trademark of the Novartis Corporation. ®FLAVOR TABS is a registered trademark of Novartis AG. ©2008 Merial Limited, Duluth, GA. All rights reserved. HGD08PBINFHEARTAD.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Guest Editorial ❯❯ C. A. Tony Bufﬁngton, DVM, MS, PhD, DACVN, The Ohio State University

Some People Use Data Like Drunks Use Lampposts: More for Support Than Illumination There’s an old joke, one variation of which is

A drunk loses the keys to his house and is looking for them under a lamppost. A policeman comes over and asks what he’s doing. “I’m looking for my keys,” he says. “I lost them over there.” The policeman looks puzzled. “Then why are you looking for them all the way over here?” “Because the light is so much better.” We humans are a complicated bunch. We evolved from other primates as a social species living in small groups with a strong dominance hierarchy, and we seem to retain far more of the attributes necessary for survival in such groups than we might admit (or imagine). We have used emotion—our feelings about what happens to us—to guide our behavior for many millennia. Very recently (within the past 1000 years or so), another method of understanding what is happening to us has emerged. We call this method the scientific method. The scientific method has helped us construct a more reliable, consistent, and externally valid representation of the world. The method developed with the recognition that personal and cultural influences affect our perceptions and interpretations of observed phenomena. It relies on agreed-upon procedures and criteria to minimize emotional influences when developing a “map” of reality, while remaining cognizant that the map is not the territory. I think of the scientific method as a strategy to separate what I know from what I think (or feel) I know.

The scientific method generally comprises four consecutive, essential steps: observation, hypothesis, experiment, and conclusion. The conclusion also commonly provides the observation for the next cycle of the method. Importantly, the scientific method disproves hypotheses about observations. It permits conclusions to be drawn, theories tested, and knowledge acquired in an evolutionary process wherein weak, mistaken, and limited hypotheses are cast aside, leaving those with the greatest explanatory power—until something with greater explanatory power comes along. The scientific method uses data for illumination, whereas our ancient drives for acquisition of resources (safety, food, sex, power, etc.) may motivate their use for support. And while our heritage may not permit us to escape the emotions associated with our actions (for example, eight of the Ten Commandments prohibit behaviors), we may at least come to better recognize their presence. Instances wherein data are used more for support than for illumination do occur in veterinary medicine, often when the emotional drive for resources conflicts with the rational presentation of data. As in other areas of our lives, money and power are common sources of this conflict, especially in relationships between commercial and academic entities. For example, I have had data “embargoed” because a corporate sponsor did not like what they showed and have been pressured to include or exclude certain data during “sponsored” talks. My experiences are not unique; withholding of key contrary data by medical companies has been reported prominently

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Guest Editorial in the media. Scientific and medical societies have become so concerned that many now require speakers to disclose all relationships with commercial enterprises, including their own. Restriction of data also occurs within the scientific and medical communities— in a slightly different fashion, but for the same reasons. For example, intense competition for ever-scarcer research funding has led some investigators to conduct only “safe” experiments, which risks reporting only results that support more funding. Even universities now aggressively market data to the press, ignoring or minimizing their limitations in an effort to gain status and resources. This state of affairs recently motivated the US National Institutes of Health to revise its proposal review standards to help return research to the “high risk, high payoff” enterprise it must be. Both scientific and emotional ap proaches provide important assistance in navigating our world. The challenge is in recognizing how they interact and overlap. The following are a few examples of the myriad situations that may raise our index of suspicion that data are being used for support (emotional reasons) rather than illumination (scientific ones): The presenter generated the data (most of us love our data like children, making objectivity impossible). The presenter relies on clinical experience or testimonial support as adequate evidence to support his or her claims. Vague summaries of results are presented, or results are published outside the peer-reviewed literature (e.g., abstracts), reported without explanation, or declared to be “on file.” Single studies of small samples are provided. Statistics are absent or confusing, or their “significance” does not match their clinical relevance. Reports of results do not clearly describe the limitations, present in all studies, that influence the interpretability of the study. Acceptance of the data results in gain to the presenter, often at others’ expense.

We also must recognize our own conscious and unconscious responses to presentations of data; after all, we share the emotional heritage of the presenter. Although our response to the presentation of information may be conscious, most information (maybe 95%) transmitted to our brains is perceived, processed, and acted on emotionally, outside of consciousness. Our own history and attitudes toward the subject and the presenter, the context in which the data are presented, and our expectations of the utility of the data and their interpretation toward our own ends all influence our receptivity or resistance to the information. These reactions can lead to our practicing, as Isaacs and Fitzgerald1 put it, eminence-, vehemence-, eloquence- (or elegance-), providence-, diffidence-, nervousness-, or (particularly for surgeons) confidence-based medicine, as opposed to evidence-based medicine. Fortunately, we can monitor our unconscious responses by using our emotional reactions for their diagnostic value. When we experience strong positive or negative feelings during the presentation of data, we can decide whether our response is to the content of the presentation or to other factors. In a way, this is where evidence-based medicine starts: our efforts to identify and interpret data. And although evidence-based medicine has its detractors and limitations, at its best, it provides a useful tool to guide one’s thinking about the utility of data in situations pertinent to one’s practice. Data represent information, and we may be the preeminent informationgathering species; after all, we have millions of years of experience with using information for support. Given that we have only a thousand years or so with using it for illumination, maybe we’re doing pretty well with our new skill already and have the potential to get even better with practice. Reference 1. Isaacs D, Fitzgerald D. Seven alternatives to evidence based medicine. BMJ 1999;319:1618.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Month-long ﬂea protection in a chewable tablet

Fast-acting

Convenient

Family-friendly

Doesn’t wash off

• Starts killing ﬂeas in 30 minutes • 100% effective within 4 hours in a controlled laboratory study • Approved by the FDA and available by prescription only To learn more about Comfortis®, see your Lilly representative or distributor representative, call 1 (888) LillyPet or visit www.comfortis4dogs.com The most common adverse reaction recorded during clinical trials was vomiting. Other adverse reactions were decreased appetite, lethargy or decreased activity, diarrhea, cough, increased thirst, vocalization, increased appetite, redness of the skin, hyperactivity and excessive salivation. For product label, including important safety information, see page 56. ©2009 Eli Lilly and Company CF00305 010109

Section Namee

At a Glance Risk Factors for Gastric Dilatation–Volvulus Page 60

Overview of the Veress Needle and Hasson Technique for Obtaining Abdominal Access Page 60

Laparoscopic-Assisted Gastropexy Page 61

Laparoscopic Gastropexy Page 63

Dr. Rawlings discloses that he has received ﬁnancial support from Biovision, Covidien, Ellman International, Endoscopic Support Services, and Karl Storz Veterinary Endoscopy.

Laparoscopic-Assisted and Laparoscopic Prophylactic Gastropexy: Indications and Techniques ❯❯ Jeffrey J. Runge, DVM University of Pennsylvania

❯❯ Philipp Mayhew, BVM&S, MRCVS, DACVS Columbia River Veterinary Specialists Vancouver, Washington

❯❯ Clarence A. Rawlings, DVM, PhD, DACVSa The University of Georgia

astric dilatation–volvulus (GDV) is open surgical gastropexy techniques have a syndrome characterized by rapid been described: tube, circumcostal, belt accumulation of gas or food in the loop, muscular ﬂap, gastrocolopexy, and stomach, increased intragastric pressure incisional. Because of the high mortality and wall tension, and rotation of the rate associated with the development of stomach about its long axis. Gastric dis- GDV, these procedures may be used protention unleashes a series of potentially phylactically in dogs that have not had GDV lethal pathophysiologic events, the most but are considered to be at high risk.8,9 important of which are compression of Studies have indicated that a prophylacthe portal and caudal vena caval venous tic gastropexy can result in a twofold to blood ﬂow, gastric necrosis, tissue aci- 30-fold reduction in lifetime mortality assodosis, cardiac arrhythmia, disseminated ciated with GDV for rottweilers and Great intravascular coagulation, and hypoten- Danes, respectively.10 sive and cardiogenic shock.1 For dogs Recent advances in veterinary medicine that develop GDV, surgical correction have included a move toward more miniis strongly recommended. Among those dogs, mortality remains high (15% to TO LEARN MORE 33%), even with aggressive resuscitative management.2–5 A gastropexy is the creation of a permanent adhesion between the gastric antrum and the adjacent right body wall. Failure to perform a gastropexy at the time of surgery for GDV correction results in a >50% recurrence rate,4 whereas performing a prophylactic gastropexy during corrective surgery for GDV decreases the recurrence rate by 4% to 10%.4,6,7 As a result, gastropexy is now considered the standard of care.4 Several

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

For a detailed description of abdominal access using a Veress needle or the Hasson technique, see the August 2008 Surgical Views article, “Canine Laparoscopic and LaparoscopicAssisted Ovariohysterectomy and Ovariectomy.” This article is available at CompendiumVet.com.

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What do dogs who take VETORYL (trilostane) have in common? ®

Results like these.

Prior to VETO RYL treatment

Effective treatment for Cushing’s syndrome is now FDA approved. You now have easy access to the most powerful ^LHWVU PU [OL ÄNO[ HNHPUZ[ JHUPUL *\ZOPUN»Z syndrome. VETORYL Capsules are the only licensed treatment available for both pituitary-dependent and adrenal-dependent hyperadrenocorticism.

treatment Following 3 months of with VETORYL

VETORYL Capsules contain the active ingredient trilostane, which blocks the excessive production of cortisol. Daily administration of VETORYL can greatly reduce the clinical signs associated with Cushing’s syndrome, enhancing the quality of life for both dog and owner. For more information, visit www.VETORYL.com. Contact your local veterinary distributor to order VETORYL Capsules today!

Following 9 months of treatment with VETO RYL

(trilostane)

Photographs courtesy of Carlos Melian, DVM, PhD

VETORYL is a trademark of Dechra Ltd. ©2009, Dechra Ltd. NADA 141-291, Approved by FDA (Z ^P[O HSS KY\NZ ZPKL LMMLJ[Z TH` VJJ\Y 0U ÄLSK Z[\KPLZ [OL TVZ[ JVTTVU ZPKL LMMLJ[Z YLWVY[LK ^LYL WVVY YLK\JLK HWWL[P[L ]VTP[PUN SL[OHYN` diarrhea, and weakness. Occasionally, more serious side effects, including severe depression, hemorrhagic diarrhea, collapse, hypoadrenocortical crisis, VY HKYLUHS ULJYVZPZ Y\W[\YL TH` VJJ\Y HUK TH` YLZ\S[ PU KLH[O =,;69@3 *HWZ\SLZ HYL UV[ MVY \ZL PU KVNZ ^P[O WYPTHY` OLWH[PJ VY YLUHS KPZLHZL or in pregnant dogs. Refer to the prescribing information for complete details or visit www.VETORYL.com. VTYL0209-01-47122-CPD

See Page 60 for Product Information Summary

VETORYL Capsules (trilostane) ®

30 mg and 60 mg strengths Adrenocortical suppressant for oral use in dogs only

BRIEF SUMMARY (For Full Prescribing Information, see package insert.) CAUTION: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. DESCRIPTION: VETORYL is an orally active synthetic steroid analogue that blocks production of hormones produced in the adrenal cortex of dogs. INDICATIONS: VETORYL Capsules are indicated or the treatment of pituitary-dependent hyperadrenocorticism in dogs. VETORYL Capsules are indicated for the treatment of hyperadrenocorticism due to adrenocortical tumor in dogs. CONTRAINDICATIONS: The use of VETORYL Capsules is contraindicated in dogs that have demonstrated hypersensitivity to trilostane. Do not use VETORYL Capsules in animals with primary hepatic disease or renal insufficiency. Do not use in pregnant dogs. Studies conducted with trilostane in laboratory animals have shown teratogenic effects and early pregnancy loss. WARNINGS: In case of overdosage, symptomatic treatment of hypoadrenocorticism with corticosteroids, mineralocorticoids and intravenous fluids may be required. Angiotensin-converting enzyme (ACE) inhibitors should be used with caution with VETORYL Capsules, as both drugs have aldosterone-lowering effects which may be additive, impairing the patient’s ability to maintain normal electrolytes, blood volume and renal perfusion. Potassium-sparing diuretics (e.g., spironolactone) should not be used with VETORYL Capsules as both drugs have the potential to inhibit aldosterone, increasing the likelihood of hyperkalemia.

QuickNotes Predisposition to GDV has been demonstrated for several breeds.

HUMAN WARNINGS: Keep out of reach of children. Not for human use. Wash hands after use. Do not empty capsule contents and do not attempt to divide the capsules. Do not handle the capsules if pregnant or if trying to conceive. Trilostane is associated with teratogenic effects and early pregnancy loss in laboratory animals. In the event of accidental ingestion/overdose, seek medical advice immediately and take the labeled container with you. PRECAUTIONS: Hypoadrenocorticism can develop at any dose of VETORYL Capsules. A small percentage of dogs may develop corticosteroid withdrawal syndrome within 10 days of starting treatment. Mitotane (o,p’-DDD) treatment will reduce adrenal function. Experience in foreign markets suggests that when mitotane therapy is stopped, an interval of at least one month should elapse before the introduction of VETORYL Capsules. The use of VETORYL Capsules will not affect the adrenal tumor itself. Adrenalectomy should be considered as an option for cases that are good surgical candidates. ADVERSE REACTIONS: The most common adverse reactions reported are poor/reduced appetite, vomiting, lethargy/dullness, diarrhea, and weakness. Occasionally, more serious reactions including severe depression, hemorrhagic diarrhea, collapse, hypoadrenocortical crisis, or adrenal necrosis/rupture may occur, and may result in death.

(trilostane) Distributed by: Dechra Veterinary Products 7015 College Boulevard, Suite 525 Overland Park, KS 66211 www.VETORYL.com 866-933-2472 VETORYL is a trademark of Dechra Ltd. © 2009, Dechra Ltd. NADA 141-291, Approved by FDA

mally invasive procedures, and the use of laparoscopic surgery for creating a less invasive prophylactic gastropexy has been investigated. These techniques can be performed in isolation or in conjunction with surgical sterilization. Laparoscopic-assisted,11 laparoscopic,12–14 and endoscopic15 gastropexy techniques have proven successful. The clinical outcome of a reported laparoscopic-assisted gastropexy16 indicated a persistent attachment between the stomach and the body wall with few complications and effective prophylaxis against GDV development. Studies reveal that an intracorporeally sutured laparoscopic gastropexy can be performed safely and effectively and has less impact on the dog’s postoperative activity level than a laparoscopic-assisted gastropexy.13 However, the adhesion strength and long-term outcome of the intracorporeally sutured laparoscopic technique have not yet been evaluated.13 In this article, we describe the techniques for laparoscopic-assisted and laparoscopic gastropexy.

Risk Factors for Gastric Dilatation–Volvulus A breed predisposition has been demonstrated for Great Danes, German shepherds, standard poodles, Weimaraners, Saint Bernards, Gordon setters, Irish setters, bassett hounds, Airedale terriers, Irish wolfhounds, borzois, bloodhounds, Akitas, and bull mastiffs.2,3 Large,

Overview of the Veress Needle and Hasson Technique for Obtaining Abdominal Access BOX 1

The Veress needle has a blunt-tipped, spring-loaded stylet within a sharp-tipped needle. As it is advanced through the body wall, the sharp tip penetrates the abdominal musculature; once within the peritoneal cavity, the spring-loaded protective stylet is deployed, thus minimizing risk of iatrogenic organ damage when the abdominal cavity is penetrated. Peritoneal insufﬂation can then be performed through the needle, followed by trocar placement. The Hasson technique uses a blunt cannula in a trocar–cannula assembly that is passed through a very small incision, usually created in a subumbilical location. Once the peritoneum has been sharply penetrated, the trocar–cannula assembly is advanced into the abdomen, pointing to the right side to minimize the risk of splenic laceration. If a 5-mm telescope and instrumentation are used, a 6-mm trocar–cannula assembly should be placed ﬁrst.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Laparoscopic-Assisted Gastropexy To perform a laparoscopic-assisted gastropexy, place the dog in dorsal recumbency and clip and aseptically prepare the abdomen from the xiphoid cartilage to the brim of the pubis. Abdominal access can be obtained by use of a Veress needle or the Hasson technique (BOX 1). If the Hasson technique is used, a blunt cannula must be employed for initial port placement. If a pneumoperitoneum has already been established through the use of a Veress needle, a sharp cannula can be used for this purpose. A pneumoperitoneum is usually established with carbon dioxide, using a mechanical insufflator that allows controlled insufflation and intraabdominal pressure monitoring. The intraabdominal pressure measured with the insufflator should not be allowed to exceed 10 to 15 mm Hg while the trocars are placed; it should then be reduced to 6 to 8 mm Hg, or just sufficient to maintain an optical space, during the laparoscopic portion of the gastropexy. Place a 0° or 30° 5-mm laparoscope through the subumbilical port, just lateral to the right margin of the rectus abdominus and 3 to 5 cm caudal to the last rib (FIGURE 1). The second trocar–

FIGURE 1

QuickNotes Dietary risk factors that can lead to the development of GDV include food characteristics and feeding practices or behaviors.

Patient positioned in dorsal recumbency. The camera port is placed on the midline just caudal to the umbilicus. The instrument port is placed just lateral to the right margin of the rectus abdominus and 3 to 5 cm caudal to the last rib. Courtesy of Clarence Rawlings, DVM, PhD, DACVS.

cannula assembly should be large enough to accommodate 10-mm instrumentation. Transilluminate the incision site to identify and avoid abdominal wall vessels. Nerves parallel vessels; thus, avoiding the vessels reduces the risk of hemorrhage and nerve injury. Pass a 10-mm laparoscopic Babcock or DuVall (FIGURE 2) forceps through the instrument port to manipulate the cranial abdominal organs and obtain an unobstructed view of the antrum of the stomach. Then grasp the FIGURE 2

10-mm DuVall laparoscopic forceps are useful for grasping the antrum of the stomach.

Courtesy of Clarence Rawlings.

mixed-breed dogs are also predisposed. Various non–breed-associated risk factors have been shown to be associated with GDV. Nondietary risk factors include lean body condition, older age, male sex, increased thoracic depth-to-width ratio, first-degree relative with GDV, aggressive or fearful temperament, histologic evidence of inflammatory bowel disease, and increased hepatogastric ligament length.15 Dietary risk factors that can lead to the development of GDV include food characteristics— small food particle size and the presence of oil or fat among the first four ingredients of a dry food—and feeding practices or behaviors, including feeding a large amount of food, once-daily feeding, feeding from an elevated bowl, eating quickly, and aerophagia.15 Based on these risk factors, it may be reasonable to conclude that certain canine subpopulations are at such a high risk of developing GDV that they could be considered good candidates to receive prophylactic treatment.

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Section Name

FIGURE 3

The antrum of the stomach is grasped using 10-mm Babcock or DuVall forceps.

Courtesy of Clarence Rawlings.

FIGURE 4

antrum of the stomach with the forceps midway between the mesenteric and antimesenteric sides, approximately 5 to 7 cm oral to During antral exteriorization, take care to the pylorus (FIGURE 3). This is also the site for avoid twisting. Place stay sutures at either end of the proposed seromuscular incision in the stomincisional gastropexy. ach to aid in exposure. These stay sutures are later Once you have a firm hold on the antrum, removed before closure. evacuate the pneumoperitoneum. Exteriorize the forceps and antrum by removing the right- the mucosa to ensure that the sutures are not side cannula and extending the port incision to placed through the mucosa into the lumen 4 to 5 cm in an orientation parallel to the last and that adequate muscle tissue is exposed rib. During this dissection, use of a muscle- for the gastropexy. Place two simple, continusplitting approach to the external and internal ous lines of 2-0 or 0 synthetic, monofilament, abdominal oblique muscles by incising parallel absorbable suture to appose both margins of to the orientation of their fibers may result in the seromuscular layer in the antrum to the less postoperative pain. The transversus abdo- transversus abdominus muscle (FIGURE 6). Before closure, remove the full-thickness minis is the final layer to be sectioned before the stomach can be exteriorized. During the stay sutures. Close the oblique abdominal musantral exteriorization, take care to avoid twist- cles with interrupted or continuous sutures of ing. As soon as the stomach is visualized, place synthetic, absorbable material, and close the a full-thickness stay suture of 2-0 absorbable remainder of the incision in routine fashion. or nonabsorbable monofilament suture in the After completion, briefly reestablish the pneustomach wall. The forceps can be released at moperitoneum and view the gastropexy laparoscopically to ensure that this point. Place a second stay optimal positioning and orisuture 4 to 5 cm orally or aboSURGICAL entation have been achieved rally. The relative positions of VIDEO and that excessive hemorthese sutures define the extent rhage or body wall defects are of the proposed gastropexy not present (FIGURE 7). (FIGURE 4). To see a video of exteriorizaMake an incision at least 4 After once more evacuattion of the stomach wall, stay suture placement, and initial cm long through the seromusing the pneumoperitoneum, suturing of the seromuscular cular layer of the antrum along remove the midline canlayer of the stomach wall to the long axis of the stomach, nula and close the incision the transversus abdominis avoiding the larger blood ves(FIGURE 8). Closure of any muscle, visit the Web port-site incisions that are 5 sels emerging from the greater Exclusives section of mm or larger should include and lesser curvatures (FIGURE CompendiumVet.com. 5). Dissect this incision from body wall closure to avoid the

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Section Name

An incision is made through the seromuscular layer (SM) of the antrum along the long axis of the stomach, exposing the underlying gastric mucosa (GM).

Courtesy of Clarence Rawlings.

FIGURE 6

Courtesy of Clarence Rawlings.

FIGURE 5

Placement of the two simple continuous suture lines through the seromuscular layer (SM) of the antral region of the stomach to the transversus abdominus (TA) muscle. (GM = gastric mucosa)

a laparoscopic hernia stapler to close the tunnel opening with three to six staples placed possibility of incisional herniation of abdomi- individually while apposing the tissues with nal viscera. a grasping instrument12; alternatively, a modiﬁcation of this method has been described in Laparoscopic Gastropexy which the imperforate stoma resulting from the Use of Intracorporeal Stapling Devices anastomosis of the two tunnels was closed Place the dog in dorsal recumbency, clip and with an intracorporeal simple interrupted aseptically prepare the abdomen, and estab- suture pattern of 2-0 or 3-0 nonabsorbable lish a pneumoperitoneum. Place three 10- to monofilament suture material.11 There are significant disadvantages to 12-mm cannulae in the caudal aspect of the right side of the abdomen. Hold the ventral an intracorporeally stapled gastropexy. aspect of the gastric antrum with laparoscopic Full-thickness perforation of the gastric grasping forceps and make a 2- by 5-cm sub- wall was seen in 14% of cases in one study.12 mucosal tunnel with laparoscopic Metzenbaum This complication could lead to contaminascissors and laparoscopic Kelly forceps, using tion and abscess formation. This technique both sharp and blunt dissection. Make a simi- can also be associated with prolonged surgical time.12 A fur ther lar-sized tunnel in the adjacent disadvantage relates to the right lateral abdominal wall SURGICAL significant cost of using disbetween the transverse and VIDEO posable stapling devices. internal abdominal oblique muscles caudal to the last rib. Use of Intracorporeal Insert a 35-mm gastrointestiTo see a video of the Suturing nal anastomosis laparoscopic incisions in the transversus In this totally laparoscopic stapler (Endo-GIA, Covidien abdominis and seromuscular tech nique, the gastropexy is Inc, Mansﬁeld, MA) into the layer of the stomach, visit the created using intracorporeal dissected tunnels and staWeb Exclusives section of suturing techniques alone, ple the stomach to the right CompendiumVet.com. which, while requiring relaabdominal wall. You can use

QuickNotes There are signiﬁcant disadvantages to an intracorporeally stapled gastropexy.

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Section Name

FIGURE 8

The gastropexy site is viewed laparoscopically to confirm correct position without twisting and to rule out excessive hemorrhage and open defects in the body wall.

QuickNotes Intracorporeal suturing is more technically challenging than laparoscopic-assisted gastropexy.

Courtesy of Clarence Rawlings.

FIGURE 7

Postoperative view of the laparoscopic-assisted gastropexy site.

tively little disposable equipment, do require sion in the seromuscular layer of the stomach. some speciďŹ c instruments. Apart from routine These incisions should be 4 to 5 cm long and laparoscopic equipment, two laparoscopic be adjacent to each other in an orientation needle holders (Szabo-Berci 5-mm, 33-cm lap- parallel to the ventral midline (FIGURE 10). Introduce an approximately 30-cm length aroscopic parrot-jaw needle holders, Karl Storz Endoscopy) are needed to complete the sutur- of 2-0 polyglactin 910 suture on a curved or ski-type needle into the peritoneal cavity by ing successfully. Establish a camera port in a subumbilical passing the needle through the body wall adjalocation as previously described, then estab- cent to the gastropexy site. First, suture the lish two 6-mm instrument ports on midline, lateral wall of the incisions in the transversus one 3 to 4 cm caudal to the xiphoid process abdominis muscle and antrum using a simple and the other midway between the two other continuous pattern. While tying knots, evacuports and directly medial to the traditional site ate the pneumoperitoneum to decrease tension and ensure secure knots and tight suture for open gastropexy (FIGURE 9). Pass a length of 2-0 nylon suture on a lines. Once the lateral margins of the incision 38-mm reverse-cutting 3/8 -circle curved nee- have been sutured, introduce a second piece dle percutaneously at the intended site of of suture and suture the medial margins to the gastropexy, 2 to 3 cm caudal to the last complete the gastropexy. Once suturing is rib and 5 to 8 cm lateral to midline. Grasp complete, remove the stay suture. Close the the needle with a laparoscopic needle holder three midline ports in routine fashion after the within the peritoneal cavity and take a deep, pneumoperitoneum has been evacuated. full-thickness bite through the antrum of the This technique is more technically chalstomach. Then pass the suture back through lenging than laparoscopic-assisted gastropexy the abdominal wall adjacent to its previous and requires the use of some specialized point of entry. This stay suture equipment (i.e., the laparois used as a temporary anchor scopic needle holders). It is SURGICAL to appose the stomach to the more time consuming, but it VIDEO body wall during incising and may be associated with less suturing. postoperative discomfort To see a video of suturing Make the first incision in because it avoids the parameand knot tying using laparothe transversus abdominis dian incision used in the lapscopic needle holders, visit muscle using laparoscopic aroscopic-assisted technique the Web Exclusives section Metzenbaum scissors. Then and therefore reduces tissue of CompendiumVet.com. make a partial-thickness incitrauma.13

Compendium: Continuing Education for VeterinariansÂŽ | February 2009 | CompendiumVet.com

Section Name

Courtesy of Philipp Mayhew.

FIGURE 10

Courtesy of Philipp Mayhew, BVM&S, MRCVS, DACVS.

FIGURE 9

A partial-thickness incision made in the seromuscular layer of the stomach and the transversus abdominis.

are associated with less tissue trauma and postoperative pain than open celiotomy. All the techniques require the use of basic Positions of the three ports used for the laparoscopic equipment and some specialintracorporeally sutured laparoscopic gasized training. We would advise veterinartropexy technique. The most caudal port is in ians wishing to perform these techniques a subumbilical location and is initially used as the to seek further specialized training. In the camera port. Once the two instrument ports are created, the camera is moved to the middle port. case of the totally laparoscopic techniques, some experience with intracorporeal suturConclusion ing using simulators or cadavers is recomIt is generally accepted that all the laparo- mended before performing these procedures scopic techniques described in this article on client-owned animals.

References 1. Burrows CG, Ignaszewski A. Canine gastric dilation-volvulus. J Small Anim Pract 1990;31:495-501. 2. Brockman DJ, Washabau RJ, Drobatz KJ. Canine gastric dilatation/volvulus syndrome in a veterinary critical care unit: 295 cases (1986–1992). JAVMA 1995;207:460-464. 3. Glickman LT, Glickman NW, Pérez CM, et al. Analysis of risk factors for gastric dilatation and dilatation-volvulus in dogs. JAVMA 1994;204(9):1465-1471. 4. Glickman LT, Lantz GC, Schellenberg DB, Glickman NW. A prospective study of survival and recurrence following the acute gastric dilatation-volvulus syndrome in 136 dogs. JAAHA 1998;34(3):253-259. 5. Beck JJ, Staatz AJ, Pelsue DH, et al. Risk factors associated with short-term outcome and development of perioperative complications in dogs undergoing surgery because of gastric-dilatation-volvulus: 166 cases (1992-2003). JAVMA 2006;229:19341939. 6. Ellison GW. Gastric dilatation volvulus. Surgical prevention. Vet Clin North Am Small Anim Pract 1993;23(3):513-530. 7. Hosgood G. Gastric dilatation-volvulus in dogs. JAVMA 1994; 204(11):1742-1747. 8. MacCoy DM, Sykes GP, Hoffer RE, et al. A gastropexy technique for permanent ﬁxation of the pyloric antrum. JAAHA 1982;18:763-768. 9. Fallah AM, Lumb WV, Nelson AW, et al. Circumcostal gas-

tropexy in the dog: a preliminary study. Vet Surg 1982;11:9-12. 10. Ward MP, Patronek GJ, Glickman LT. Beneﬁts of prophylactic gastropexy for dogs at risk of gastric dilatation-volvulus. Prev Vet Med 2003;60(4):319-329. 11. Rawlings CA. Laparoscopic-assisted gastropexy. JAAHA 2002;38(1):15-19. 12. Sánchez-Margallo FM, Díaz-Güemes I, Usón-Gargallo J. Intracorporeal suture reinforcement during laparoscopic gastropexy in dogs. Vet Rec 2007;160(23):806-807. 13. Hardie RJ, Flanders JA, Schmidt P, et al. Biomechanical and histological evaluation of a laparoscopic stapled gastropexy technique in dogs. Vet Surg 1996;25(2):127-133. 14. Mayhew PD, Brown DC. Prospective evaluation of two intracorporeally sutured prophylactic laparoscopic gastropexy techniques compared to laparoscopic-assisted gastropexy in dogs. Vet Surg 2009; in press. 15. Dujowich M, Reimer SB. Evaluation of an endoscopically assisted gastropexy technique in dogs. JAVMA 2008;232(7):1025. 16. Rawlings CA, Mahaffey MB. Prospective evaluation of laparoscopic-assisted gastropexy in dogs susceptible to gastric dilatation. JAVMA 2002;221:1576-1581. 17. Raghavan M, Glickman NW, Glickman LT. The effect of ingredients in dry dog foods on the risk of gastric dilatation-volvulus in dogs. JAAHA 2006;42(1):28-36.

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Reading Room

HIS MAMMOTH WORK has been changed substantially from its second edition, which was published just 5 years previously. Both the material and the format have been updated, and a companion “e-dition” is now available. However, as in the previous editions, the number of contributors has been carefully limited, and the format for text and art remains consistent throughout.

Despite its size and scope, meticulous organization provides ready access to the desired material. Title: Small Animal Surgery, 3rd ed. Editors: Theresa Welch Fossum, Cheryl S. Hedlund, Ann L. Johnson, Kurt S. Schulz, Howard B. Seim III, Michael D. Willard, Anne Bahr, Gwendolyn L. Carroll Publisher: Mosby-Elsevier Year: 2007 Pages: 1610 ISBN: 978-0-323-04439-4

TO LEARN MORE For further information about this book or to order a copy, visit

www.us.elsevierhealth.com.

The book contains 41 chapters, material, disease classification, etioldivided into four sections. The first part ogy, clinical signs, diagnosis, general concerns general surgical principles treatment, analgesia, anesthesia/sedaand targets general practitioners and tion, antibiotics, calculations, comstudents. Topics include sterile tech- plications, and key points. There are nique, surgical instruments, preopera- more than 2100 high-quality illustrative and postoperative care, rational tions, 75% of which are in color. antibiotic use, analgesia, and physiThe e-dition contains the complete cal rehabilitation. The remaining three contents of the printed book, plus sections cover soft tissue surgery (i.e., weekly updates and extra topics, specific organs and systems), orthope- such as less commonly performed dic surgery, and neurosurgery. In each procedures. The Web site is fully case, a general discussion is followed searchable. There are also tools for by chapters on specific conditions. note-taking, saving searches, and Various techniques are described for viewing and saving images in a performing the same procedure when PowerPoint format. Furthermore, the applicable. The basic chapter structure viewer can watch video clips and proceeds from general discussion (e.g., surgical simulations. The e-dition is definitions, surgical anatomy, antibiot- available as a stand-alone product. ics/analgesics, surgical procedure) to This volume is truly impressive. specific diseases (e.g., diagnosis, med- Despite its massive size and scope, ical management, surgical treatment meticulous organization and an and techniques, complications). Many abundance of visual cues provide new procedures have been added, and ready access to the desired matemore advanced surgery is described, rial and rapid scanning of relevant even though general practitioners points. It will undoubtedly serve as will probably refer such cases; more an invaluable resource for a fresh complex operations are appropri- look at the most common proceately marked. Overall, descriptions of dures and a gateway to new and anatomy, conditions, and procedures less common techniques. apply to all small animals, with differences between SHARE YOUR COMMENTS species noted as needed. Have a question or comment about Important features in the this book? Let us know: book are highlighted with E-MAIL editor@CompendiumVet.com “note” boxes in each chapter, and all boxes and tables are FAX 800-556-3288 color-coded. In addition, there WEB CompendiumVet.com are icons for text on general

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The Use of Probiotics in Managing GI Problems and Supporting Intestinal Health Suzanne Nolt Mansour, DVM Best Friend Veterinary Hospital Braselton, Georgia

Patient: Lucy, a 2-year-old basset hound

Therapy Plan: We treated Lucy with an anthelmintic for the hookworms, a coccidiostat for the coccidia, and several antibiotics for the mastitis. When we got her, Lucy was underweight at only 29 lb, and we had a hard time getting her to gain weight. We decided to add Purina Veterinary Diets® FortiFlora® brand Canine Nutritional Supplement to her food. Within a week, her diarrhea began to improve. Outcome: My mother decided to adopt her. Lucy’s stool was still a little loose and bloody, so my mother continued to supplement her food with FortiFlora. After only about 3 or 4 days, Lucy’s stool started to firm up, and the blood resolved. Lucy now weighs 45 lb and is doing well at home. We didn’t get Lucy’s diarrhea cleared up until we were able to restore the healthy balance of microbes in her gastroin testinal tract. For tiFlora def initely helped manage the problem—and got her health back to normal—far more quickly than if we hadn’t used it. This information has not been peer reviewed and does not necessarily reflect the opinions of, nor constitute or imply endorsement or recommendation by, the Publisher or Editorial Board. The Publisher is not responsible for any data, opinions, or statements provided herein.

History: In September 2007, we rescued an underweight Lucy from a breeder after she developed mastitis postpartum. She had hookworm and coccidia infections, an umbilical hernia, and stress colitis. She also suffered from chronic, bloody diarrhea.

Lucy Veterinarian’s Comments

I use Purina Veterinary Diets® FortiFlora® as a nutritional supplement whenever a patient’s intestines aren’t functioning properly and when we’re giving antibiotics to treat infections. Supplementing these patients with FortiFlora helps reduce the risk of diarrhea. When using FortiFlora, we can sometimes avoid using antibiotics in nonspecific diarrhea cases. We have a lot of clients who are into holistic or natural medicine for themselves and their pets, so FortiFlora fits perfectly into that kind of philosophy. I recommend the nutritional supplement because it helps bolster an animal’s immune response. So many of our treatments are much more effective if we promote a strong immune system. FortiFlora does just that. I have been prescribing FortiFlora for more than 2 years now and have treated hundreds of animals. We have not had a single client return it because the dog or cat wasn’t eating, and we haven’t had a single complaint that the supplement wasn’t working. FortiFlora is a safe and reliable way to manage many problems I see on a regular basis in my practice, and I have confidence recommending it to my clients. Sponsored by

Behavior

Behavior Assessment: Completing the Examination

About This Column

❯❯ Sharon L. Crowell-Davis, DVM, PhD, DACVB,* The University of Georgia

Behavior problems are a signiﬁcant cause of death (euthanasia) in companion animals. While most veterinary practices are necessarily geared toward the medical aspect of care, there are many opportunities to bring behavior awareness into the clinic for the beneﬁt of the pet, the owner, and ourselves. This column acknowledges the importance of behavior as part of veterinary medicine and speaks practically about using it effectively in daily practice.

The ﬁrst two articles in this series on assessing behavior patients explored the use of history forms and owner interviews to gather information about history, environment, other problems, and owner commitment to treatment. This article addresses direct observation and evaluation of the patient, including interaction with the owner, veterinary staff, and other pets.

Understanding

o understand the relationship between a behavior patient and its owner, comprehensive information about any prior training the patient has received and the degree to which the owner can affect the pet’s behavior through verbal commands is critical. This information is often also important in understanding the development of behavior problems, particularly for dogs. Although most dogs undergo some degree of obedience training, the amount and level of that training can vary widely, from a few sessions conducted by the owner based on tips from a book, DVD, or TV show to many hours of formal training conducted or supervised by a professional. As with many other issues of pet behavior, such as getting “mad,” clear, explicit descriptions are essential to knowing exactly how the animal was trained. If the owners state that positive reinforcement was used, ask exactly what type of positive reinforcement and when. For example, food treats may have been unsuccessful either because they were not sufﬁciently palatable (e.g., dry kibble) or because they were so highly palatable that the pet became extremely excited, resulting in a decreased response to training. Likewise, owners may say that aversive training techniques or punishment were not used because a trainer they consulted told them that leash corrections involving jerking a choke chain against the trachea did not hurt.

QuickNotes

*Dr. Crowell-Davis discloses that she has received ﬁnancial support from CEVA Animal Health.

CompendiumVet.com | February 2009

Detailed, speciﬁc information about the patient’s training history should be obtained.

Sometimes dogs that have been trained using strictly positive reinforcement techniques and are calm during training act very fearful during unstructured interactions with their owners. This is because, in the structured training situation, the owner’s behavior is more predictable and reliable for the dog, whereas during unstructured interactions the dog may be unsure of what the owner is going to do. For a fearful dog, uncertainty about what is going to happen can exacerbate both fear and aggression. If a pet knows how to do a trick on command, the reliability of the interaction during the trick may be useful in treating a variety of behavior problems. For example, one dog with fear aggression that presented to my office only relaxed and exhibited body language indicative of a nonfearful state when family members asked it to “high five” by holding their hand, palm forward, near the dog while saying that phrase. The dog would then raise its paw to touch the hand. All other attempts by family members to initiate interaction with the dog resulted in the dog exhibiting various signs of fear, including laying its ears back against its head, lowering its head and/or tail, growling, and occasionally snapping or biting. During early phases of treatment for the fear aggression, frequent requests to “high five” were used to increase the amount of positive interaction between the dog and the family.

Observing the Patient in the Office Much can be learned by directly observing the patient during the owner interview, while the attention of all the people in the room is superficially directed to each other. For example, cats are typically brought to the clinic in carriers. I usually ask the client to set the carrier on the floor with the door open. Because the veterinarian’s office is a strange and intimidating place, many cats remain in the carrier. Over a period of minutes, some gradually

stick their nose out, then their head, and finally exit the carrier very cautiously. A few bolder cats come out more rapidly. Whether and how the cat leaves the carrier is useful information for identifying how timid or bold the animal is. Allowing the cat to leave the security of the carrier when it is ready to also gives it the opportunity to gradually familiarize itself with the room. If two or more cats are presented for QuickNotes fighting at home, observing how they freely interact in the veterinary office In the examination can sometimes be useful; however, it room, some informais usually helpful to obtain the own- tion about the pet’s er’s opinion on the advisability of this temperament can be approach. If the owner believes that gathered by observthe cats fight only under very specific ing its response to circumstances that are unlikely to be its environment, its replicated in the veterinarian’s office, behavior toward its useful information can be obtained by letting the cats out in the office and owners, and its interobserving how they signal each other— actions with clinicians which one stares and which one looks and hospital staff. away; which one walks boldly across the middle of the room and which one hides in a corner or under a chair; which one holds its ears stiffly upright and rotated to the side and which one tucks its ears back against its head. However, if the owner has any concern that the cats might fight in the office, it is best not to let them interact directly. Dogs that are brought in for evaluation should initially be kept on leash and, if there is a history of aggression, in a basket muzzle. If the history does not indicate any background of aggressiveness or excessive fear of strangers, 2 or 3 minutes of observing the dog’s demeanor while on leash in the examination room should be sufficient to verify whether it is safe for the dog to be allowed loose. Allowing the dog to explore the room and people in it is desirable, if it is safe. While the dog is off leash in the examination room, the clinician and staff can develop a rapport with the dog by giving it treats. If the history indicates that TO LEARN the dog should know the correct MORE responses to basic commands (e.g., sit, down), the clinician and staff can test these responses. If a The previous articles in nonaggressive dog has a problem this series, “Behavior Assessment: History Forms with jumping into people’s laps, and Interviews” (December the technique of discouraging this 2008) and “Behavior behavior by repeatedly standing Assessment: The First up and turning one’s back to the Appointment” (January dog can be demonstrated to the 2009) are available at owner. However, some dogs are CompendiumVet.com. so intimidated by strangers or nov-

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Understanding

Behavior

elty that they will hide underr ently to specific movements the owner’s chair or refuse or to specific people? Are In cases of extremely fearto leave the owner’s lap. the dog’s reactions consisful or aggressive patients If the history indicates tent with the history? If so, a any degree of aggression, orr stimulus discrimination (e.g., that appear to be physically if the initial behavior of the fear of men, fear of people healthy when observed dog when it enters the exam-wearing hats) may be conination room indicates that firmed. If the reactions are and not touched, and for it might become aggressive,, inconsistent with the history, then the dog should remain the dog’s behavior problem which the owners report restrained on leash by the may be in response to a no physical signs or history owners. Diagnosis can be more general set of stimuli. facilitated by observing the of trauma, subjecting the Observing the Pet at Home dog’s signaling. For example,, patient to a physical examiThe development of inexdoes it prick its ears toward pensive video cameras has the clinician or pin them nation on the fi rst visit may been of great benefit to back against its head? Does the practice of veterinary it hold its tail low or high? cause excessive stress, behavior. Many pet owners Does it show its teeth? If so,, making the physical examiown a video camera (digihow? (Lifting the rostral lips tal or tape) or can borrow off the incisors and canines nation counterproductive. one. While a great deal can may indicate strong self-be learned from interviewconfidence and dominance,, whereas pulling the commissure of the lip caudally ing people who know the patient and observing to expose the premolars and even the molars usu- the patient in the exam room, some behaviors can ally indicates strong fear.) Does the dog react differ- only be fully understood by observing the pet in its regular environment. In some of these cases, a home visit is adequate. However, home visits are often impractical, and in many cases, the pet may not exhibit the undesired behavior when a stranger is in the house. Asking the owner to make a video of the pet’s behavior at home is beneficial in many situations, such as cases of conflict between two or more pets, particularly during specific situations that only occur in the home. Videotaping the pets in this context may provide critical information about their relationship, especially when the owners do not have a good understanding of normal, speciesspecific behavior. For example, two dogs presented to my clinic for fighting. The written descriptions provided by the owner suggested that the dogs were simply engaging in vigorous wrestling play. However, I could not be entirely confident of this diagnosis based only on the owner’s description. Videotaping of a “fighting” incident by the owner confi rmed that the dogs were merely engaging in very loud, boisterous play behavior. Videotapes can also verify and clarify descriptions by owners of pet behavior that is extreme or abnormal, such as a cat repeatedly throwing itself violently against a baby gate in an attempt to attack a cat on the other side of the gate.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Physical Examination Performing a physical examination is, of course, always desirable. However, touching an animal with severe fear of humans can be extremely stressful for the patient. If the owner reports that he or she has not observed any physical signs of illness (e.g., vomiting, diarrhea, coughing, sneezing, runny eyes, lumps) and the patient looks physically healthy, but the patient is likely to have an extreme response to a physical examination, such as violent trembling, struggling, or screaming, the potential to exacerbate the behavior problem by forcefully subjecting the patient to a physical examination should be weighed against the possible beneﬁt of performing the examination. This is also the case with extremely aggressive animals. The stress caused to the patient by subjecting it to the restraints and/or medications that may be necessary to make a physical examination possible and safe for the veterinary staff may outweigh the beneﬁt of the examination. In the extreme cases that are referred to my own clinic, it is not uncommon to delay a physical examination until the second or third visit, QuickNotes when response to the iniIn many cases, it tial treatment makes it posis useful to ask the sible to examine the patient without causing it excessive client to videotape stress or placing anyone in the pet in its home undue danger. environment.

Conclusion Assessing a patient with a major behavior problem is not a quick process. Obtaining a written history provided by people familiar with the patient, directly interviewing people familiar with the patient, watching videotapes of the patient, and directly observing and interacting with the patient in the examination room are all valuable tools for gathering information. The more of these tools that can be used in assessing a patient with a behavior problem, the more likely it is that the problem can be accurately diagnosed and a treatment plan that can be effectively implemented by the family can be developed.

TO LEARN MORE

For more information about how to obtain clinically relevant descriptions from owners, see the December 2008 article “Behavior Assessment: History Forms and Interviews” at CompendiumVet.com.

CompendiumVet.com | February 2009

3 CE CREDITS

CE Article 1

Oral Examination of Cats and Dogs ❯❯ Dale Kressin, DVM, DAVCD Animal Dental Center— Milwaukee and Oshkosh Glendale, Wisconsin

At a Glance Examination of the Awake Patient Page 72

Examination of the Anesthetized Patient Page 77

Tooth Identiﬁcation Systems for Use in Dogs and Cats Page 79

WEB EXCLUSIVE A downloadable anatomic checklist and sample canine and feline dental charts are available at

CompendiumVet.com.

he oral examination is an integral part Cephalic Index of every general physical examina- Skull shape and size influence the incidence tion for companion animals. Lesions of certain dental conditions.8 Understanding in the oral cavity may be clinical mani- skull classifications is important because festations of metabolic disease.1–4 Similarly, anatomic variations play a significant role the general physical examination may pro- in the extraoral and intraoral appearance vide important clues to intraoral disease and in dental occlusal relationships.9 The cephalic index categorizes dog and processes.5 A general physical examination is also fundamental to choosing the cat breeds based on skull shape and size.8,10 optimal anesthesia protocol necessary to A relatively wide, short skull characterperform a comprehensive oral examina- izes brachycephalic breeds, such as bulltion.6 In essence, the two examination dogs, shih tzus, Himalayans, and Persians. components complement each other. Mesocephalic breeds, such as Alaskan malA comprehensive oral examination amutes, German shepherds, and Labrador includes a nonsedated patient evaluation retrievers, have muzzles of intermediate of the head, neck, and oral cavity and a width and length. Dolichocephalic breeds, sedated or anesthetized intraoral evalua- represented by borzois, standard poodles, tion. A systematic approach using a dental and whippets, have relatively long, narchart with an anatomic checklist is most row muzzles. efficient. Abnormal or suspicious findings are recorded on the dental chart using Brachycephalic Breeds objective indices. This practice helps avoid Brachycephalic breeds with a complete missing important details and allows for permanent dentition often have dental comparison of findings between periodic crowding with tooth rotation and a relatively high incidence of periodontal disexaminations.7 ease.9 Dental crowding and tooth rotation Examination of the Awake Patient often result in abnormal dental eruption. The Extraoral Examination Teeth may partially erupt or fail to erupt Facial Symmetry and Related Observations and remain embedded in subgingival tisThe extraoral examination begins with sue. The first premolars are commonly a careful evaluation of facial symmetry affected, and the lower first premolars are (FIGURE 1). Palpation of the face may idenFIGURE 1 tify firm or fluctuant masses. Palpation of lymphatic and salivary tissue may reveal abnormalities related to intraoral disease. Alopecia; draining tracts; discharge; scarring; malodor from the ears, nose, mouth, or skin; and any other external findings are noted on the dental chart or anatomic checklist. Opening and closing the mouth may reveal popping and clicking sounds or crepitus within the temporomandibular joint. Asymmetric facial swelling.a Palpating the left and right mandibles may a reveal fractures or symphyseal instability. All images are courtesy of Dale Kressin, DVM, DAVCD.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

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You’re probably familiar with SevoFlo. But, do you realize the unique advantages SevoFlo carries into your surgical suite? Sevoflurane is the latest inhalant in veterinary anesthesia. SevoFlo’s low blood:gas solubility and greater range of vaporizer settings gives you rapid, precise control over the depth of anesthesia. In addition, SevoFlo doesn’t irritate airways1 and is less of a respiratory depressant than isoflurane.2 You and your clients can expect a smooth return of cognitive and motor skills—and a quick return home. To learn more about the benefits of SevoFlo and other anesthetics Abbott Animal Health offers, contact Abbott Animal Health Customer Service at 888-299-7416 or visit us at www.abbottanimalhealth.com.

Important Information: How Supplied: SevoFlo is packaged in amber colored bottles containing 250 mL sevoflurane. Indications: SevoFlo is indicated for induction and maintenance of general anesthesia in dogs. Warnings, Precautions, and Contraindications: Like other inhalation anesthetics, sevoflurane is a profound respiratory depressant. Respiration must be monitored closely in the dog and supported when necessary with supplemental oxygen and/or assisted ventilation. Due to sevoflurane’s low solubility in blood, increasing concentration may result in rapid hemodynamic changes compared to other volatile anesthetics. SevoFlo is contraindicated in dogs with a known sensitivity to sevoflurane or other halogenated agents. Adverse Reactions: The most frequently reported adverse reactions during maintenance anesthesia were hypotension, followed by tachypnea, muscle tenseness, excitation, apnea, muscle fasciculations and emesis. See package insert for full prescribing information. SEVO-184 June 2008 ©2008 Abbott Laboratories

1. T Mutoh, A Kanamura, H Suzuki, H Tsubone, R Nishimura, N Sasaki. AJVR 2001:62:311-319 2. DS Galloway JCH Ko, HF Reaugh, RE Mandsager, ME Payton, T Inoue, E Portillo. JAVMA (2004) Vol 255, No 5, 700-704

See Page 74 for Product Information Summary

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SevoFlo®

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(sevoflurane) Inhalation Anesthetic For Use in Dogs Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian. DESCRIPTION: SevoFlo (sevoflurane), a volatile liquid, is a halogenated general inhalation anesthetic drug. Its chemical name is fluoromethyl 2,2,2trifluoro-l- (trifluoromethyl) ethyl ether, and its structural formula is:

Sevoflurane Physical Constants are: Molecular weight 200.05 Boiling point at 760 mm Hg 58.6°C Specific gravity at 20°C 1.520-1.525 g/mL Vapor pressure in mm Hg at 20°C 157 at 25°C 197 at 36°C 317 Distribution Partition Coefficients at 37°C: Blood/Gas 0.63-0.69 Water/Gas 0.36 Olive Oil/Gas 47-54 Brain/Gas 1.15 Mean Component/Gas Partition Coefficients at 25°C for Polymers Used Commonly in Medical Applications: Conductive rubber 14.0 Butyl rubber 7.7 Polyvinyl chloride 17.4 Polyethylene 1.3 Sevoflurane is nonflammable and nonexplosive as defined by the requirements of International Electrotechnical Commission 601-2-13. Sevoflurane is a clear, colorless, stable liquid containing no additives or chemical stabilizers. Sevoflurane is nonpungent. It is miscible with ethanol, ether, chloroform and petroleum benzene, and it is slightly soluble in water. Sevoflurane is stable when stored under normal room lighting condition according to instructions. INDICATIONS: SevoFlo is indicated for induction and maintenance of general anesthesia in dogs. DOSAGE AND ADMINISTRATION: Inspired Concentration: The delivered concentration of SevoFlo should be known. Since the depth of anesthesia may be altered easily and rapidly, only vaporizers producing predictable percentage concentrations of sevoflurane should be used. Sevoflurane should be vaporized using a precision vaporizer specifically calibrated for sevoflurane. Sevoflurane contains no stabilizer. Nothing in the drug product alters calibration or operation of these vaporizers. The administration of general anesthesia must be individualized based on the patient’s response. WHEN USING SEVOFLURANE, PATIENTS SHOULD BE CONTINUOUSLY MONITORED AND FACILITIES FOR MAINTENANCE OF PATENT AIRWAY, ARTIFICIAL VENTILATION, AND OXYGEN SUPPLEMENTATION MUST BE IMMEDIATELY AVAILABLE. Replacement of Desiccated CO2 Absorbents: When a clinician suspects that the CO2 absorbent may be desiccated, it should be replaced. An exothermic reaction occurs when sevoflurane is exposed to CO2 absorbents. This reaction is increased when the CO2 absorbent becomes desiccated (see PRECAUTIONS). Premedication: No specific premedication is either indicated or contraindicated with sevoflurane. The necessity for and choice of premedication is left to the discretion of the veterinarian. Preanesthetic doses for premedicants may be lower than the label directions for their use as a single medication.1 Induction: For mask induction using sevoflurane alone, inspired concentrations up to 7% sevoflurane with oxygen are employed to induce surgical anesthesia in the healthy dog. These concentrations can be expected to produce surgical anesthesia in 3 to 14 minutes. Due to the rapid and dose dependent changes in anesthetic depth, care should be taken to prevent overdosing. Respiration must be monitored closely in the dog and supported when necessary with supplemental oxygen and/or assisted ventilation. Maintenance: SevoFlo may be used for maintenance anesthesia following mask induction using sevoflurane or following injectable induction agents. The concentration of vapor necessary to maintain anesthesia is much less than that required to induce it. Surgical levels of anesthesia in the healthy dog may be maintained with inhaled concentrations of 3.7-4.0% sevoflurane in oxygen in the absence of premedication and 3.3-3.6% in the presence of premedication. The use of injectable induction agents without premedication has little effect on the concentrations of sevoflurane required for maintenance. Anesthetic regimens that include opioid, alpha2-agonist, benzodiazepine or phenothiazine premedication will allow the use of lower sevoflurane maintenance concentrations. CONTRAINDICATIONS: SevoFlo is contraindicated in dogs with a known sensitivity to sevoflurane or other halogenated agents. WARNINGS: Sevoflurane is a profound respiratory depressant. DUE TO THE RAPID AND DOSE DEPENDENT CHANGES IN ANESTHETIC DEPTH, RESPIRATION MUST BE MONITORED CLOSELY IN THE DOG AND SUPPORTED WHEN NECESSARY WITH SUPPLEMENTAL OXYGEN AND/OR ASSISTED VENTILATION. In cases of severe cardiopulmonary depression, discontinue drug administration, ensure the existence of a patent airway and initiate assisted or controlled ventilation with pure oxygen. Cardiovascular depression should be treated with plasma expanders, pressor agents, antiarrhythmic agents or other techniques as appropriate for the observed abnormality. Due to sevoflurane’s low solubility in blood, increasing the concentration may result in rapid changes in anesthetic depth and hemodynamic changes (dose dependent decreases in respiratory rate and blood pressure) compared to other volatile anesthetics. Excessive decreases in blood pressure or respiratory depression may be corrected by decreasing or discontinuing the inspired concentration of sevoflurane. Potassium hydroxide containing CO2 absorbents (e.g. BARALYME®) are not recommended for use with sevoflurane. ADVERSE REACTIONS: The most frequently reported adverse reactions during maintenance anesthesia were hypotension, followed by tachypnea, muscle tenseness, excitation, apnea, muscle fasciculations and emesis. Infrequent adverse reactions include paddling, retching, salivation, cyanosis, premature ventricular contractions and excessive cardiopulmonary depression. Transient elevations in liver function tests and white blood cell count may occur with sevoflurane, as with the use of other halogenated anesthetic agents.

PRECAUTIONS: Halogenated volatile anesthetics can react with desiccated carbon dioxide (CO2) absorbents to produce carbon monoxide (CO) that may result in elevated carboxyhemoglobin levels in some patients. To prevent this reaction, sevoflurane should not be passed through desiccated soda lime or barium hydroxide lime. Replacement of Desiccated CO2 Absorbents: When a clinician suspects that the CO2 absorbent may be desiccated, it should be replaced before administration of sevoflurane. The exothermic reaction that occurs with sevoflurane and CO2 absorbents is increased when the CO2 absorbent becomes desiccated, such as after an extended period of dry gas flow through the CO2 absorbent canisters. Extremely rare cases of spontaneous fire in the respiratory circuit of the anesthesia machine have been reported during sevoflurane use in conjunction with the use of a desiccated CO2 absorbent, specifically those containing potassium hydroxide (e.g. BARALYME). Potassium hydroxide containing CO2 absorbents are not recommended for use with sevoflurane. An unusually delayed rise in the inspired gas concentration (decreased delivery) of sevoflurane compared with the vaporizer setting may indicate excessive heating of the CO2 absorbent canister and chemical breakdown of sevoflurane. The color indicator of most CO2 absorbent may not change upon desiccation. Therefore, the lack of significant color change should not be taken as an assurance of adequate hydration. CO2 absorbents should be replaced routinely regardless of the state of the color indicator. The use of some anesthetic regimens that include sevoflurane may result in bradycardia that is reversible with anticholinergics. Studies using sevoflurane anesthetic regimens that included atropine or glycopyrrolate as premedicants showed these anticholinergics to be compatible with sevoflurane in dogs. During the induction and maintenance of anesthesia, increasing the concentration of sevoflurane produces dose dependent decreases in blood pressure and respiratory rate. Due to sevoflurane’s low solubility in blood, these changes may occur more rapidly than with other volatile anesthetics. Excessive decreases in blood pressure or respiratory depression may be related to depth of anesthesia and may be corrected by decreasing the inspired concentration of sevoflurane. RESPIRATION MUST BE MONITORED CLOSELY IN THE DOG AND SUPPORTED WHEN NECESSARY WITH SUPPLEMENTAL OXYGEN AND/OR ASSISTED VENTILATION. The low solubility of sevoflurane also facilitates rapid elimination by the lungs. The use of sevoflurane in humans increases both the intensity and duration of neuromuscular blockade induced by nondepolarizing muscle relaxants. The use of sevoflurane with nondepolarizing muscle relaxants has not been evaluated in dogs. Compromised or debilitated dogs: Doses may need adjustment for geriatric or debilitated dogs. Because clinical experience in administering sevoflurane to dogs with renal, hepatic and cardiovascular insufficiency is limited, its safety in these dogs has not been established. Breeding dogs: The safety of sevoflurane in dogs used for breeding purposes, during pregnancy, or in lactating bitches, has not been evaluated. Neonates: The safety of sevoflurane in young dogs (less than 12 weeks of age) has not been evaluated. HUMAN SAFETY: Not for human use. Keep out of reach of children. Operating rooms and animal recovery areas should be provided with adequate ventilation to prevent the accumulation of anesthetic vapors. There is no specific work exposure limit established for sevoflurane. However, the National Institute for Occupational Safety and Health has recommended an 8 hour time-weighted average limit of 2 ppm for halogenated anesthetic agents in general. Direct exposure to eyes may result in mild irritation. If eye exposure occurs, flush with plenty of water for 15 minutes. Seek medical attention if irritation persists. Symptoms of human overexposure (inhalation) to sevoflurane vapors include respiratory depression, hypotension, bradycardia, shivering, nausea and headache. If these symptoms occur, remove the individual from the source of exposure and seek medical attention. The material safety data sheet (MSDS) contains more detailed occupational safety information. For customer service, adverse effects reporting, and/or a copy of the MSDS, call (888) 299-7416. CLINICAL PHARMACOLOGY: Sevoflurane is an inhalational anesthetic agent for induction and maintenance of general anesthesia. The Minimum Alveolar Concentration (MAC) of sevoflurane as determined in 18 dogs is 2.36%.2 MAC is defined as that alveolar concentration at which 50% of healthy patients fail to respond to noxious stimuli. Multiples of MAC are used as a guide for surgical levels of anesthesia, which are typically 1.3 to 1.5 times the MAC value. Because of the low solubility of sevoflurane in blood (blood/gas partition coefficient at 37°C = 0.63-0.69), a minimal amount of sevoflurane is required to be dissolved in the blood before the alveolar partial pressure is in equilibrium with the arterial partial pressure. During sevoflurane induction, there is a rapid increase in alveolar concentration toward the inspired concentration. Sevoflurane produces only modest increases in cerebral blood flow and metabolic rate, and has little or no ability to potentiate seizures.3 Sevoflurane has a variable effect on heart rate, producing increases or decreases depending on experimental conditions.4,5 Sevoflurane produces dose-dependent decreases in mean arterial pressure, cardiac output and myocardial contraction.6 Among inhalation anesthetics, sevoflurane has low arrhythmogenic potential.7 Sevoflurane is chemically stable. No discernible degradation occurs in the presence of strong acids or heat. Sevoflurane reacts through direct contact with CO2 absorbents (soda lime and barium hydroxide lime) producing pentafluoroisopropenyl fluoromethyl ether (PIFE, C4H2F6O), also known as Compound A, and trace amounts of pentafluoromethoxy isopropyl fluoromethyl ether (PMFE, C5H6F6O), also known as Compound B. Compound A: The production of degradants in the anesthesia circuit results from the extraction of the acidic proton in the presence of a strong base (potassium hydroxide and/or NaOH) forming an alkene (Compound A) from sevoflurane. Compound A is produced when sevoflurane interacts with soda lime or barium hydroxide lime. Reaction with barium hydroxide lime results in a greater production of Compound A than does reaction with soda lime. Its concentration in a circle absorber system increases with increasing sevoflurane concentrations and with decreasing fresh gas flow rates. Sevoflurane degradation in soda lime has been shown to increase with temperature. Since the reaction of carbon dioxide with absorbents is exothermic, this temperature increase will be determined by the quantities of CO2 absorbed, which in turn will depend on fresh gas flow in the anesthetic circle system, metabolic status of the patient and ventilation. Although Compound A is a dose-dependent nephrotoxin in rats, the mechanism of this renal toxicity is unknown. Two spontaneously breathing dogs under sevoflurane anesthesia showed increases in concentrations of Compound A as the oxygen flow rate was

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decreased at hourly intervals, from 500 mL/min (36 and 18 ppm Compound A) to 250 mL/min (43 and 31 ppm) to 50 mL/min (61 and 48 ppm).8 Fluoride ion metabolite: Sevoflurane is metabolized to hexafluoroisopropanol (HFIP) with release of inorganic fluoride and CO2. Fluoride ion concentrations are influenced by the duration of anesthesia and the concentration of sevoflurane. Once formed, HFIP is rapidly conjugated with glucuronic acid and eliminated as a urinary metabolite. No other metabolic pathways for sevoflurane have been identified. In humans, the fluoride ion half-life was prolonged in patients with renal impairment, but human clinical trials contained no reports of toxicity associated with elevated fluoride ion levels. In a study in which 4 dogs were exposed to 4% sevoflurane for 3 hours, maximum serum fluoride concentrations of 17.0-27.0 mcmole/L were observed after 3 hours of anesthesia. Serum fluoride fell quickly after anesthesia ended, and had returned to baseline by 24 hours post-anesthesia. In a safety study, eight healthy dogs were exposed to sevoflurane for 3 hours/day, 5 days/week for 2 weeks (total 30 hours exposure) at a flow rate of 500 mL/min in a semi-closed, rebreathing system with soda lime. Renal toxicity was not observed in the study evaluation of clinical signs, hematology, serum chemistry, urinalysis, or gross or microscopic pathology. DRUG INTERACTIONS: In the clinical trial, sevoflurane was used safely in dogs that received frequently used veterinary products including steroids and heartworm and flea preventative products. Intravenous Anesthetics: Sevoflurane administration is compatible with barbiturates, propofol and other commonly used intravenous anesthetics. Benzodiazepines and Opioids: Benzodiazepines and opioids would be expected to decrease the MAC of sevoflurane in the same manner as other inhalational anesthetics. Sevoflurane is compatible with benzodiazepines and opioids as commonly used in surgical practice. Phenothiazines and Alpha2-Agonists: Sevoflurane is compatible with phenothiazines and alpha2- agonists as commonly used in surgical practice. In a laboratory study, the use of the acepromazine/oxymorphone/ thiopental/sevoflurane anesthetic regimen resulted in prolonged recoveries in eight (of 8) dogs compared to recoveries from sevoflurane alone. CLINICAL EFFECTIVENESS: The effectiveness of sevoflurane was investigated in a clinical study involving 196 dogs. Thirty dogs were mask-induced with sevoflurane using anesthetic regimens that included various premedicants. During the clinical study, one hundred sixty-six dogs received sevoflurane maintenance anesthesia as part of several anesthetic regimens that used injectable induction agents and various premedicants. The duration of anesthesia and the choice of anesthetic regimens were dependent upon the procedures that were performed. Duration of anesthesia ranged from 16 to 424 minutes among the individual dogs. Sevoflurane vaporizer concentrations during the first 30 minutes of maintenance anesthesia were similar among the various anesthetic regimens. The quality of maintenance anesthesia was considered good or excellent in 169 out of 196 dogs. The table shows the average vaporizer concentrations and oxygen flow rates during the first 30 minutes for all sevoflurane maintenance anesthesia regimens: Average Vaporizer Concentrations among Anesthetic Regimens

Average Vaporizer Concentrations among Individual Dogs

3.31 - 3.63%

1.6 - 5.1%

Average Oxygen Flow Rates among Anesthetic Regimens 0.97 - 1.31 L/minute

Average Oxygen Flow Rates among Individual Dogs 0.5 - 3.0 L/minute

During the clinical trial, when a barbiturate was used for induction, the times to extubation, sternal recumbency and standing recovery were longer for dogs that received anesthetic regimens containing two preanesthetics compared to regimens containing one preanesthetic. Recovery times were shorter when anesthetic regimens used sevoflurane or propofol for induction. The quality of recovery was considered good or excellent in 184 out of 196 dogs. Anesthetic regimen drug dosages, physiological responses, and the quality of induction, maintenance and recovery were comparable between 10 sighthounds and other breeds evaluated in the study. During the clinical study there was no indication of prolonged recovery times in the sighthounds. HOW SUPPLIED: SevoFlo (sevoflurane) is packaged in amber colored bottles containing 250 mL sevoflurane, List 5458. STORAGE CONDITIONS: Store at controlled room temperature 15°-30°C (59°-86°F). REFERENCES: 1. Plumb, D.C. ed., Veterinary Drug Handbook, Second Edition, University of Iowa Press, Ames, IA: p. 424 (1995). 2. Kazama, T. and Ikeda, K., Comparison of MAC and the rate of rise of alveolar concentration of sevoflurane with halothane and isoflurane in the dog. Anesthesiology. 68: 435-437 (1988). 3. Scheller, M.S., Nakakimura, K., Fleischer, J.E. and Zornow, M.H., Cerebral effects of sevoflurane in the dog: Comparison with isoflurane and enflurane. Brit. J. Anesthesia 65: 388-392 (1990). 4. Frink, E.J., Morgan, S.E., Coetzee, A., Conzen, P.F. and Brown, B.R., Effects of sevoflurane, halothane, enflurane and isoflurane on hepatic blood flow and oxygenation in chronically instrumented greyhound dogs. Anesthesiology 76: 85-90 (1992). 5. Kazama, T. and Ikeda, K., The comparative cardiovascular effects of sevoflurane with halothane and isoflurane. J. Anesthesiology 2: 63-8 (1988). 6. Bernard, J. M., Wouters, P.F., Doursout, M.F., Florence, B., Chelly, J.E. and Merin, R.G., Effects of sevoflurane on cardiac and coronary dynamics in chronically instrumented dogs. Anesthesiology 72: 659-662 (1990). 7. Hayaski, Y., Sumikawa, K., Tashiro, C., Yamatodani, A. and Yoshiya, I., Arrhythmogenic threshold of epinephrine during sevoflurane, enflurane and isoflurane anesthesia in dogs. Anesthesiology 69: 145-147 (1988). 8. Muir, W.W. and Gadawski, J., Cardiorespiratory effects of low-flow and closed circuit inhalation anesthesia, using sevoflurane delivered with an in-circuit vaporizer and concentrations of compound A. Amer. J. Vet. Res. 59 (5): 603-608 (1998). NADA 141-103, Approved by FDA SevoFlo® is a registered trademark of Abbott Laboratories. Manufactured by Abbott Laboratories, North Chicago, IL 60064, USA Product of Japan Under license from Maruishi Pharmaceutical Co., LTD 2-3-5, Fushimi-Machi, Chuo-Ku, Osaka, Japan For customer service call (888) 299-7416. ©Abbott 8/2006 Taken from Commodity Number 03-5474/R6, SevoFlo, sevoflurane, package insert, January 11, 2007

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Oral Examination of Cats and Dogs CE CE FIGURE 2

FIGURE 3

Missing ﬁrst premolar tooth.

Oral cyst at the location of the first premolar.

frequently missing bilaterally (FIGURE 2). Dental radiographs are essential when evaluating animals with missing teeth to rule out embedded teeth, which may result in the formation of oral cysts 11–13 (FIGURE 3). These cysts are often locally destructive and may ultimately lead to tooth loss, jaw fracture, or other complications. Brachycephalic breeds also exhibit anatomic variations associated with chronic obstructive respiratory syndrome (CORS).14 These variations include hyperplasia and elongation of the soft palate, eversion of the lateral saccules, stenotic nares, tracheal hypoplasia, and laryngeal collapse.15 Evaluation for CORS should be performed before intubation and without tongue retraction. The soft palate should not extend caudal to the tip of the epiglottis. Everted laryngeal saccules appear as off-white mush roomshaped structures rostral to (in front of) the vocal cords. Laryngeal collapse is identified as medial tipping of the corniculate processes and flattening of the cuneiform process of the arytenoid cartilage. Images and further descriptions of these structures are published elsewhere.16 Veterinarians should be prepared for anesthetic complications when working with brachycephalic patients. Tracheal intubation may be difficult because of tracheal hypoplasia, and partial airway obstruction may complicate anesthesia recovery. Brachycephalic patients should remain intubated as long as possible and should be monitored continuously after extubation to ensure normal breathing.17 Brachycephalic feline breeds seem to be at increased risk for developing nasal aspergillosis–penicilliosis.18

Mesocephalic Breeds

Dental crowding and periodontal disease are less common in mesocephalic breeds. The mesocephalic facial profile is intermediate between the brachycephalic and dolichocephalic profiles. Mesocephalic breeds have an increased incidence of missing premolars, especially the first and fourth premolars. To confirm that missing teeth are not simply unerupted, dental radiographs should always be obtained when teeth appear to be missing. Unerupted teeth can result in dentigerous cysts. Dolichocephalic Breeds

Dolichocephalic breeds may exhibit caudal (posterior) crossbite, a malocclusion in which the upper fourth premolars (the carnassial teeth) are positioned lingual to the lower ﬁ rst molars rather than the normal buccal orientation.10 This condition is particularly common in collies.19 It may result in less effective “shearing” activity of the carnassial teeth, leading to increased accumulation of plaque and calculus20 and, ultimately, periodontal disease. Young to middle-aged dolichocephalic animals may be at increased risk of developing fungal (Aspergillus fumigatus) infections of the nasal passages compared with animals with other skull shapes.21 These animals initially present with a unilateral hemorrhagic and mucopurulent nasal discharge that often becomes bilateral with disease progression. Depigmentation of the nasal planum may occur. Manipulation of the nose is often painful for these animals. Rhinoscopy, computed tomography, and fungal cultures help establish the diagnosis.

QuickNotes An oral examination should be part of every thorough physical examination. Veterinarians must be familiar with normal anatomy and variations between breeds to be able to identify potential problems.

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FIGURE 4

Feline oral examination.

(A) Secure the head at the zygomatic arch, holding gently but firmly. (B) Pet the cat’s chin gently to provide reassurance. (C) Open the mouth. (D and E) Use a cotton-tipped applicator to protect fingers from injury while obtaining a clear view. (F) View of hard palate. Note the rugae (folds).

The Intraoral Examination

QuickNotes Using patience and a gentle technique during the oral examination allows optimal visualization of oral structures and identiﬁcation of potential problems while avoiding injury to the evaluator and patient.

The initial examination of both cats and dogs is attempted with the mouth closed. To avoid injury to the patient and the examiner, it is helpful to have an assistant restrain the patient. The upper and lower lips are viewed and then gently separated to get views of the dentition, oral mucosa, and dental occlusion. Front and side views of the oral cavity may allow observation of some surfaces of all of the teeth. I use a 6-inch cotton-tipped applicator to help avoid personal injury while viewing oral anatomy. For cats, I prefer to sit or stand directly behind the patient. To reduce stress and help comfort the cat, I speak softly and gently pet the cat’s head and neck before palpating the neck and mandibular lymph nodes. I then tilt the cat’s head back to point the nose toward the ceiling. This relaxes the lower jaw, which I gently pull down with a ﬁnger to open the mouth. I can then view the oral cavity (FIGURE 4). For dogs, I approach from the side, using gentle techniques to relax the patient. Many dogs respond favorably to their name spoken in a slow, calm, soft voice. Repeated gentle petting can also be reassuring. An assistant

gently secures the dog’s head and body while I perform a closed-mouth examination from the front and both sides (FIGURE 5). The assistant then holds the mandible and maxilla in the premolar region to slowly and gently encourage the dog to open its mouth. Allowing a dog to open and close its own mouth helps with the awake oral examination. Forcing the mouth open and holding it open results in patient resistance and difficulty for the examiner; therefore, in my practice, we do not force the mouth into an open position. Caution and patience are strongly advised. Some fearful or aggressive animals require chemical restraint. The gingiva, alveolar mucosa, cheek mucosa, lips, palate, incisive papilla, tongue, and floor of the mouth are briefly viewed during the awake patient oral examination. Any discharge, discoloration, draining tract, fistula, foreign body, inflammation, mass, swelling, fracture, or ulceration should be noted on the dental chart. These abnormalities can be investigated further after the animal is sedated or under anesthesia. The awake patient intraoral examination can be very revealing. All observed abnormali-

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Oral Examination of Cats and Dogs CE CE FIGURE 5

Canine oral examination.

(A) Front view of gingiva. Note the mucogingival line separating the attached gingiva from the free alveolar mucosa. (B) Right-side oral mucosa. (C) Left-side oral mucosa.

ties should be discussed with clients to help Equipment and Instrumentation convey the importance of performing a com- A comprehensive intraoral examination requires prehensive intraoral examination under gen- an adequate light source with magnification, a eral anesthesia. Diagnostics help to establish Finoff transilluminator or bright penlight, a denan accurate diagnosis and carry out an opti- tal radiography machine, periodontal explorer probes, appropriate anesthesia equipment mal treatment plan. and supplies, atraumatic tissue retractors, and Examination of the Anesthetized Patient mouth gags. An adequately sized, uncluttered Anesthesia allows a meticulous, systematic work area is preferred to avoid distraction of approach to the intraoral examination. The larynx, the evaluator. oropharynx, tonsils, soft palate (FIGURE 6), hard palate, incisive papilla, gingiva, alveolar mucosa, Evaluation of the Occlusion buccal mucosa, tongue, floor of the mouth, and While performing the intraoral examination, salivary structures can all be visualized. After the examiner must answer the following questhorough scaling (above and below the gum tions to determine whether findings are norline) and polishing, the teeth, along with the mal or further evaluations are indicated. periodontal tissue, are evaluated visually, by tactile probing, by dental radiography, and by Is the bite right? The patient is first evalutransillumination. The number, color, shape, ated for a normal occlusion (“scissors bite”) size, and condition of the teeth are assessed. with the mouth closed.22–25 In a normal canine The use of objective indices allows for consis- occlusion, the upper incisors overlap the lower incisors, with the coronal tips of the lower tent dental evaluations. incisors resting on the cingulum of the upper FIGURE 6 incisors. The lower canines should fit into the diastema (space) between the upper canines and the adjacent third incisors without contact between any teeth. The upper and lower premolars should interdigitate, with the lower premolars positioned rostral to the upper opposing teeth. The coronal tips of the lower premolars are positioned in the interdental spaces of the upper premolars, and these opposing teeth do not come into contact. The lower fourth premolar cusp tip is positioned between the upper third and fourth premolars. The preceding third, second, and first premolars have the same relationship bilaterally. The crown cusps Soft palate defect. Note the purulent discharge.

QuickNotes The use of a systematic approach and objective indices enables a meaningful evaluation of dental, periodontal, oral, and extraoral tissue. All abnormal ﬁndings should be recorded on a dental chart or anatomic checklist.

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QuickNotes Dental radiographs and periodontal probing are fundamental diagnostic tests used in the oral examination. Ancillary tests may help establish a deﬁnitive diagnosis for treatment planning.

of the lower premolars are positioned lingual of the upper fourth and third premolars. The to the opposing premolars of the upper dental teeth in the upper and lower arches do not arches. The mesial crown cusp of the upper come into coronal contact. The lower third and fourth premolar is positioned lateral to the fourth premolars are oriented lingual to the interdental space of the lower first molar and premolars of the upper dental arch. The upper the adjacent fourth premolar. fourth premolar in cats is positioned similar to Adult cats have occlusal relationships simi- that in dogs. The mesial aspect of the crown lar to those in dogs; however, they have fewer cusp of the upper fourth premolar is positeeth. When the normal adult feline occlu- tioned lateral to the interdental space of the sion is viewed from the front with the mouth lower molar and the adjacent fourth premolar closed, the upper incisors slightly overlap the tooth. The orientation of the upper fourth prelower incisors or have direct coronal contact. molars is clinically significant. Cats often presThe lower canines fit into the narrow diastema ent with mandibular mucosal “oral masses” or between the upper canines and the adjacent “lesions” as a result of occlusal trauma. third incisors. When the occlusion is viewed from the side with the mouth closed, the rela- Do the teeth occlude functionally and atrautionship of the upper and lower premolars is matically? Traumatic malocclusions, such as similar to that in dogs; however, cats normally tooth-on-tooth or tooth-on-soft tissue contact,9 have two fewer premolars and molars on each can be very painful for companion animals. mandible and one less premolar and one less Traumatic malocclusion is particularly common molar on each upper dental arch. (Sample when there is a discrepancy in jaw length or a feline and canine dental charts are available variation in tooth position. at CompendiumVet.com.) The lower premolar teeth are oriented rostral to the upper premolar Is the number of teeth present normal? teeth, and the crown cusp of the lower fourth Missing or supernumerary teeth must be recpremolar is positioned in the interdental space ognized and charted.9 Dental radiographs are needed to establish the correct diagnosis.

Eruption Times for Deciduous and Permanent Teeth in Cats and Dogs22 TABLE 1

Eruption of Deciduous Teeth (weeks of age)

Eruption of Permanent Teeth (months of age)

Incisors

3–4

3–5

Canines

4–6

Premolars

4–12

4–6

Molars

None

5–7

Incisors

2–3

3–4

Canines

3–4

4–5

Premolars

3–6

4–6

Molars

None

4–5

Dogs

Cats

Do the teeth appear normal? Abnormal tooth structure (enamel defects or fractures), shape (malformations), or discoloration may be identiﬁed. Fractured and worn teeth may be present. All of these abnormal ﬁndings should be charted.

Number of Teeth Fundamental knowledge of the normal deciduous, permanent, and mixed (deciduous and permanent) dentition is necessary to perform the oral examination. A basic understanding of deciduous and permanent tooth eruption (TABLE 1) and the normal number of teeth (BOX 1) is important to be able to differentiate between normal and abnormal development.22 I prefer to start the dental examination with the patient in left lateral recumbency and evaluate the right upper and lower dental arches for the full complement of teeth. There should be one canine and three incisors on each side of each arch. On the upper arch, the right upper fourth premolar is the largest tooth. In adult dogs, the third, second, and ﬁrst premolars are found in successive positions rostral to

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Oral Examination of Cats and Dogs CE CE the fourth premolar, and the first and second molars are immediately caudal to the fourth premolar. Adult cats have three upper premolars and one upper molar. On the lower arch, the first molar is the largest tooth. In adult dogs, the four lower premolars are rostral to the first molar, and the second and third lower molars are caudal to it. Adult cats have two lower premolars and one lower molar. I then evaluate the left side and compare it with the right side. Missing teeth are circled on the dental chart, and supernumerary teeth are drawn on the chart in the locations where they are observed.

Plaque, Calculus, and Periodontal Disease Accumulations of plaque and calculus, the presence of gingival inflammation, furcation exposure, and tooth mobility are noted on the dental chart. A furcation is the space between two roots of the same tooth. Periodontal disease results in bone loss, which exposes the furcation. Furcation exposure and tooth mobility are important findings that suggest advanced periodontal disease or other pathology. Tooth mobility can also be related to root fracture, metabolic disease, or neoplasia.26 Periodontal probing and dental radiographs are needed to evaluate the extent of periodontal disease. To make evaluations simple and consistent between periodic oral examinations and between evaluators, calculus, plaque, and gingival indices (BOXES 2, 3, AND 4) are used. Tooth furcation and mobility indices (BOXES 5 AND 6) with periodontal disease staging (BOX 7) may also be recorded. I use a three-point index or stage for each assessment (four stages for periodontal disease) and chart only abnormal findings. For plaque and calculus, stage 1 indicates a relatively small amount, with 2 and 3 indicating moderate and heavy accumulations, respectively. Gingival stages of 1, 2, and 3 indicate minimal, moderate, and significant inflammation. The furcation, gingival, mobility, and periodontal disease stages are recorded next to each tooth, whereas the plaque and calculus indices are general assessments of the full dentition. It is important to recognize areas of the dentition that have particularly heavy accumulations of plaque and calculus compared with the contralateral side, as these may indicate inadequate occlusal function or lack of chew-

BOX 1

Tooth Identification Systems for Use in Dogs and Cats5,8 The Anatomic Tooth Identification System These dental formulas are used to evaluate for the full complement of teeth. Each formula denotes the teeth on one side. The upper number represents the upper dental arch; the lower number, the lower arch. The total number of teeth is determined by multiplying the formula total by two because the left and right sides are symmetric. Dogs Deciduous dentition: i 33 c 11 p 33 m 00 = 28 Permanent dentition: I 33 C 11 P 44 M 23 = 42 Cats Deciduous dentition: i 33 c 11 p 32 m 00 = 26 Permanent dentition: I 33 C 11 P 32 M 11 = 30 c = deciduous canine, C = permanent canine, i = deciduous incisor, I = permanent incisor, m = deciduous molar, M = permanent molar, p = deciduous premolar, P = permanent premolar The Modified Triadan Systema I use the modified Triadan system for medical records. For case reports sent to referring veterinarians, I use both the anatomic and modified Triadan systems to avoid misunderstanding. The modified Triadan system can be used for all species. The system for veterinary use is based on three-digit numbers because the upper dental arches of dogs normally have 10 teeth and the lower arches have 11 teeth. In this system, the dental arches are numbered from the right upper (100), to the left upper (200), to the left lower (300), and finally to the right lower (400). Individual teeth are then numbered successively from the most rostral to the most caudal tooth. For example, the incisor adjacent to the facial midline of the upper right dental arch is numbered 101, while the right lower first incisor adjacent to the mandibular symphysis is numbered 401. The adjacent incisors on the right side are numbered 102 and 103 (upper arch) and 402 and 403 (lower arch), respectively. All cuspids or canine teeth are numbered 04, all fourth premolar teeth are numbered 08, and the first molars are numbered 09. In dogs, the four right lower premolars from rostral to caudal are numbered 405, 406, 407, and 408. The right lower molars from rostral to caudal are numbered 409, 410, and 411, respectively. In cats, gaps are left in the numbering sequence for the teeth that are normally absent. For example, the right upper first premolar observed in normal feline dentition is numbered 106 because 105 is absent. From rostral to caudal on the right upper dental arch, the adjacent teeth are designated 107, 108 (the third and fourth premolars, respectively), and 109 (the only molar tooth). On the right lower dental arch, the first encountered premolar tooth is numbered 407 (405 and 406 are absent), the adjacent premolar (the fourth premolar) is labeled 408, and the most caudal mandibular tooth is labeled 409 (the only molar tooth). a See the charts at CompendiumVet.com for an example of the modified Triadan numbering system in use.

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ing due to oral pain or other causes. Regional disparity between objective indices necessitates careful observation, tactile assessments, and full-mouth dental radiographs. Periodontal and explorer probes are used for tactile assessments of teeth and periodontal tissue assessment.27 Explorer probes are made with various working ends. A number 17 explorer probe is useful for subtle evaluation of enamel, dentin, and cementum or evidence of pulp exposure.7 The shepherd’s hook explorer probe is useful for the evaluation of dental integrity and evidence of pulp exposure. BOX 2

Modiﬁed Ramfjord Calculus Index44 CI-0: No calculus; not charted CI-1: Minimal supragingival calculus deposition CI-2: Moderate subgingival and supragingival calculus deposition CI-3: Heavy calculus deposits on crown and subgingivally BOX 3

Plaque Index44 PI-0: No plaque; not charted PI-1: Minimal gray-tan plaque deposits PI-2: Moderately dense gray-tan plaque deposits PI-3: Heavy plaque deposition exudes from gingival sulcus BOX 4

Gingival Index44 GI-0: Normal gingival shape and color; not charted GI-1: Mild gingival inflammation, swelling, slight red color GI-2: Moderate gingival inflammation, swelling, red with bleeding GI-3: Severe gingival inflammation, swelling, bright red with bleeding

The periodontal probe is used for a threedimensional assessment of the periodontium.28 It is placed at six imaginary points of the tooth.29 I prefer to probe the buccal surface from the mesial aspect (front) to the middle point and then the distal aspect (back) of the tooth. I then position the probe at the distal aspect of the lingual or palatal surface and continue to the middle and mesial points of each tooth. With experience, periodontal probing of the four dental arches takes approximately 60 seconds with the help of a dental assistant recording abnormal ﬁndings on the dental chart.30

Tooth Color Tooth color depends on dental care, diet, age, and other factors.5 Professional and home dental care reduces accumulations of plaque and calculus that affect tooth color. Dietary factors can inﬂuence accumulations of plaque and calculus as well as introduce biochemicals that may affect tooth color. I often see patients with tooth surfaces that are discolored red or black, presumably from minerals in local water supplies (FIGURE 7). Young cats and dogs have teeth with wide pulp chambers and thin dentin walls compared with those of older animals. As animals age, the dentin walls develop (or enlarge), resulting in greater tooth density with a yellow, tan, or off-white appearance. Elderly patients may develop sclerotic dentin and pulp chamber shrinkage, which may result in a glassy or transparent appearance of the teeth. The outer enamel layer of the tooth is nonliving and remains approximately the same thickness throughout the animal’s life. However, nutrition, general health, and antimicrobial therapy may affect enamel formation and, ultimately, tooth color.31 For example,

BOX 5

Furcation Indexa

FIGURE 7

F-1: Furcation exposure; probe extends less than halfway under the crown in any direction of a multirooted tooth with attachment loss F-2: Moderate furcation exposure; probe extends more than halfway under the crown of a multirooted tooth with attachment loss but not all the way through F-3: Extensive furcation exposure; probe passes from one side all the way through (through-and-through exposure) a American Academy of Periodontology. Clinical Periodontology. 2nd ed. New York: Thieme Medical Publishers; 1989.

Black mineral deposits within calculus contribute to tooth discoloration.

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Oral Examination of Cats and Dogs CE tetracycline administration during tooth development may affect the formation of hydroxyapatite of permanent teeth. Changes related to enamel abrasion and attrition also affect tooth color.22 Infectious disease, malnutrition, or trauma may disrupt normal enamelogenesis and result in enamel defects31 (FIGURE 8). These defects can result in irregular dentin formation and plaque and calculus retention, which contribute to tooth discoloration. Extraoral or intraoral occlusal trauma may result in tooth wear, fractures, or pulpitis. Dentin responds to chronic trauma by producing reparative (tertiary) dentin.32 Reparative dentin increases the tooth density and affects FIGURE 8

tooth color. The pulp responds to trauma with inﬂammation as an attempt to repair itself; however, pulp necrosis with tooth discoloration frequently occurs. Teeth that are purple, pink, tan, brown, black, or just off-white should be evaluated further. Discolored teeth may have reversible or irreversible pulpitis (FIGURE 9) or may be nonvital.33 Discolored teeth should be evaluated tactilely with an explorer probe for dentin or pulp exposure and with dental radiographs for endodontic pathology.34 Transillumination of discolored teeth may help determine tooth vitality,22 particularly in younger patients. I use a Finoff transilluminator to direct light through the potentially nonvital tooth. A pink glow indicates illumination of blood ﬂowing through the pulp and is consistent with tooth vitality. A tooth that appears relatively dark and does not have a pink glow when compared with adjacent and contralateral teeth is likely nonvital. Transillumination is an inexact procedure in older patients because of the variability in tooth density.

Tooth Shape and Size Knowledge of the correct shape and size of teeth is necessary to recognize anomalous teeth,35 such as peg teeth, which are small and have a single cusp. Skulls, models, photographs,

Enamel defect. FIGURE 9

BOX 6

Mobility Indexa

Pulpitis; view of lingual aspect of lower first molar.

M-0: Normal physiologic movement (<0.2 mm), not charted M-1: Slight tooth mobility in any direction other than axial (0.2–0.5 mm) M-2: Moderate tooth mobility in any direction other than axial (0.5 to 1 mm) M-3: Severe tooth mobility in any direction other than axial (>1 mm) a

American Veterinary Dental College Nomenclature Committee.

FIGURE 10 BOX 7

Periodontal Disease Index44 Periodontal disease is staged based on the degree of periodontal destruction. Dental radiographs with periodontal probing are the fundamental diagnostic tests used.

A periodontal probe penetrates a defect in this malformed canine tooth. Note the purulent discharge and the hair embedded within the dental defect.

PD-1: Stage 1 periodontal disease; no attachment loss PD-2: Stage 2 periodontal disease; 0–25% attachment loss PD-3: Stage 3 periodontal disease; 25%–50% attachment loss PD-4: Stage 4 periodontal disease; >50% attachment loss

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and dental charts are commercially available for comparison with a patient’s dentition to help veterinarians recognize anomalous teeth. Anomalous teeth may be an incidental ﬁnding, a functional problem, or a contributing factor in the development of periodontal disease (FIGURE 10). All anomalous teeth should be probed for enamel and periodontal defects as well as radiographed for periodontal and endodontic pathology (FIGURE 11). FIGURE 11

Defects and Trauma Coronal defects may involve only the enamel, the enamel and dentin (FIGURE 12), “near pulp exposure,” or direct pulp exposure (FIGURE 13). Teeth with coronal defects often have rough surfaces with accumulations of plaque and calculus. The carnassial teeth are frequently chipped or fractured in dogs that are allowed to chew hard objects. Caged animals with separation

FIGURE 12

FIGURE 13

Anomalous lower molar. The molar cusps are short and blunted. Note the enamel defect adjacent to the gingival margin.

Fracture; dentin exposed.

Pulp exposed.

FIGURE 14

FIGURE 15

FIGURE 16

Dental abrasion due to cage chewer syndrome. Notice the severely abraded distal aspect of the canine tooth caused by chewing on the cage door. Crown therapy can help protect these teeth from dental fracture.

Severe dental attrition of a lower second molar from tooth-on-tooth wear.

Severe slab fracture of an upper fourth premolar. This is a crown-root fracture that extends below the gingival margin.

FIGURE 17

FIGURE 18

FIGURE 19

Feline tooth resorption.

Carious lesion in an upper first molar.

Draining ﬁstula apical to (above) the mucogingival line.

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Oral Examination of Cats and Dogs CE anxiety frequently incur defects or fractures on the distal surfaces of incisors, canines, and premolars while trying to escape from their cages. These defects are particularly common in dogs, and their presence has been called cage chewer syndrome (FIGURE 14). Dogs that habitually carry tennis balls develop severe dental abrasion. Dental attrition is abnormal coronal wear due to excessive mastication or chewing (FIGURE 15). Slab fracture of a carnassial tooth (FIGURE 16) frequently results in suborbital swelling. However, dental radiography should be performed before extracting the fractured tooth to ensure accurate diagnosis and treatment of the tooth or teeth causing the swelling.36 Tooth root abscess of the upper third premolar or upper first molar, foreign body penetration, and infectious or neoplastic diseases can also cause swelling and must be ruled out via dental radiography. Lingual fractures of the lower first molars are also common but are often missed during routine oral examination. Tooth resorption in cats (formerly called neck lesions, resorptive lesions, erosive lesions, or feline odontoclastic resorptive lesions) is very common37,38 (FIGURE 17). Tooth resorption occasionally occurs in dogs. Identification of tooth resorption on oral examination is a strong indication for dental radiography.39 An animal with one visible lesion is likely to have more. Dogs may have dental caries (cavities) (FIGURE 18). Dental caries may involve the crown or root but are most commonly found on the occlusive surfaces of the molars.40,41

Soft Tissue Evaluation I prefer to evaluate the soft tissue after the teeth have been evaluated. I assess all four dental arches for normal gingival color and anatomy. My initial focus is on the attached gingiva. There should be a minimum of 2 to 3 mm of attached pink gingiva around every tooth.42 Gingival defects or recession may result in less than 2 mm of attached gingiva. Gingival discoloration, inflammation, and edema may also be evident. Because the attached gingiva protects the teeth and other periodontal structures, its loss creates a risk for periodontal disease progression, endodontic disease development, and the eventual loss of adjacent teeth. The mucogingival line is a clinically important region. If discharge or fistulas are identified at or apical to the mucogingival line (FIGURE 19), endodontic disease of the adjacent tooth is likely.43 If discharge or fistulas are identified coronal to the mucogingival line, periodontal disease is suspected.43 Dental radiographs are necessary when these fistulas are identified. The buccal mucosa is carefully examined for defects, enlargements, lacerations, masses, and ulcerations. Chronic ulcerative paradental stomatitis (CUPS) is a common problem in dogs.44 It is an immune-mediated response to plaque bacteria that has also been referred to as plaque intolerance.45 These animals present with ulcerative lesions of the buccal mucosa and the tongue surfaces that come in contact with the teeth (FIGURE 20). CUPS is similar to feline stomatitis.

FIGURE 20 CUPS lesions. A

(A) Buccal ulceration. Ulceration typically occurs at locations where the mucosal tissues contact the teeth (and bacterial plaque). (B) Tongue ulceration. Note the hyperemic, ulcerated tongue margins. These lesions can be particularly painful. CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

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Conclusion An awake patient oral examination is an integral part of every physical examination. Familiarity with normal anatomy and breed variations is essential for recognizing potential problems. Abnormalities identiﬁed during the initial awake patient examination need to be investigated further. The comprehensive oral examination under anesthesia is a detailed and systematic evaluation of dental, periodontal, and oral cavity structures. The use of a dental chart with an anatomic checklist helps the evaluator avoid missing problems and allows comparison between examinations. Plaque and calculus indices are quantitative assessments of plaque and calculus

deposition on teeth. Gingival, furcation, mobility, and periodontal disease staging is useful in assessing periodontal health. These indices are charted only when problems are identified. Dental charts provide excellent documentation of the oral examination for the medical record. Dental radiographs, periodontal and dental probing, and transillumination of teeth are fundamentally important diagnostic tests used in the comprehensive oral examination. Information from the comprehensive oral examination can be used in dental consultations with clients for effective communication about necessary treatment plans for their companion animals.

References 1. Chuang S, Sung JM, Kuo SC, et al. Oral and dental manifestations in diabetic and nondiabetic uremic patients receiving hemodialysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;99(6):689695. 2. Van Nice E. Management of multiple dental infections in a dog with diabetes mellitus. J Vet Dent 2006;23(1):18-25. 3. Mealey BL. Diabetes and periodontal disease: two sides of a coin. Compend Contin Educ Dent 2000;21:943-946. 4. Jordan RCK. Diagnosis of periodontal manifestations of systemic disease. Periodontology 2000;23:217-228. 5. Oral anatomy and diagnosis. In: Wiggs RB, Lobprise HB. Veterinary Dentistry Principles and Practice. Philadelphia: LippincottRaven; 1997:87-99. 6. Muir WM. Considerations for general anesthesia. In: Thurmon J, Tranquilli W, Benson G, eds. Lumb & Jones’ Veterinary Anesthesia. 3rd ed. Baltimore: Williams & Wilkins; 1996:7-30. 7. Dental records. In: Holmstrom SE, Frost P, Eisner ER. Veterinary Dental Techniques. 2nd ed. Philadelphia: Saunders; 1998:421. 8. Gioso MA, Carvalho VG. Oral anatomy of the dog and cat in veterinary dentistry practice. Vet Clin North Am Small Anim Pract 2005;35:763-780. 9. Hale FA. Juvenile veterinary dentistry. Vet Clin North Am Small Anim Pract 2005;35:789-817. 10. Oral anatomy and physiology. In: Wiggs RB, Lobprise HB. Veterinary Dentistry Principles and Practice. Philadelphia: LippincottRaven; 1997:77-79. 11. Lobprise HL, Wiggs RB. Dentigerous cyst in a dog. J Vet Dent 1992;9(1):13-15. 12. Gioso MA, Carvalho VG. Maxillary dentigerous cyst in a cat. J Vet Dent 2003;20(1):28-30. 13. Colmerry B 3rd. The gold standard of veterinary oral health care. Vet Clin North Am Small Anim Pract 2005;35:781-787. 14. Wykes PM. Brachycephalic airway obstructive syndrome. Probl Vet Med 1991;3(2):188-197. 15. Riecks TW, Birchard SJ, Stephens JA. Surgical correction of brachycephalic syndrome in dogs: 62 cases (1991–2004). JAVMA 2007;230(9):1324-1328. 16. Done SH, Goody PC, Evans SA, Stickland NC. The Dog & Cat Color Atlas of Veterinary Anatomy. Vol 3. Philadelphia: Mosby; 1996:2.44-2.45. 17. Anesthetic considerations in patients with preexisting problems or conditions. In: Paddelford RR. Manual of Small Animal Anesthesia. 2nd ed. Philadelphia: Saunders; 1999:315-316. 18. Whitney J, Broussard J, Stefanacci JD. Four cats with fungal rhinitis. J Feline Med Surg 2005;7(1):53-58.

19. Basics of orthodontics. In: Wiggs RB, Lobprise HL. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:464-479. 20. Johnston N. Crunch time: approaches to bite abnormalities and malocclusions. Vet Times 2006 Dec 18:10-13. 21. Cohn LA. Chronic nasal discharge in dogs. Proc Atl Coast Vet Conf 2006. 22. Oral anatomy and physiology. In: Wiggs RB, Lobprise HB. Common Dental Procedures. Lakewood, CO: AAHA Press; 2000:8-9. 23. Surgeon TW. Fundamentals of small animal orthodontics. Vet Clin North Am Small Anim Pract 2005;35:869-871. 24. Hobson P. Normal occlusion in the dog. J Vet Dent 2005;22:196198. 25. Kressin DJ. Veterinary orthodontics: some cases require braces. DVM InFocus 2006 Sep:12-16. 26. Greenstein G, Polson A. Understanding tooth mobility. Compend Contin Educ Dent 1988;9:470. 27. Wiggs RB, Lobprise HB. Dental equipment. In: Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:4-27. 28. Wiggs RB, Lobprise HB. Materials and equipment. In: Common Dental Procedures. Lakewood, CO: AAHA Press; 2000:162. 29. Harvey CE, Emily PP. Periodontal disease. In: Small Animal Dentistry. St. Louis: Mosby; 1993:100-103. 30. Clinical examination. In: Tutt C. Small Animal Dentistry: A Manual of Techniques. Ames, IA: Blackwell Publishing; 2006:42-44. 31. Miles AEW, Grigson C. Enamel hypoplasia. In: Colyer’s Variations and Diseases of the Teeth of Animals. New York: Cambridge University Press; 1990:437-454. 32. Andreasen JO. Response of oral tissues to trauma. In: Textbook and Color Atlas of Traumatic Injuries to the Teeth. 3rd ed. St Louis: Mosby; 1994:77-132. 33. Hale FA. Localized intrinsic staining of teeth due to pulpitis and pulp necrosis in dogs. J Vet Dent 2001;18(1):14-20. 34. Endodontic therapy. In: Tutt C. Small Animal Dentistry: A Manual of Techniques. Ames, IA: Blackwell Publishing; 2006:215. 35. Miles AEW, Grigson C. Order Carnivora. In: Colyer’s Variations and Diseases of the Teeth of Animals. New York: Cambridge University Press; 1990:62-90. 36. Hoffman SL, Kressin DJ, Verstraete FJM. Myths and misconceptions in veterinary dentistry. JAVMA 2007;231(12):1-7. 37. Roux P, Berger M, Stoffel M, et al. Observations of the periodontal ligament and cementum in cats with dental resorptive lesions. J Vet Dent 2005:22(2):74-85. 38. Ingham KE, Gorrel C, Blackburn J, Farnsworth W. Prevalence of odontoclastic resorptive lesions in a population of clinically healthy

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Oral Examination of Cats and Dogs CE cats. J Small Anim Pract 2001;42:439-443. 39. Lommer MJ, Verstraete FJM. Prevalence of odontoclastic resorptive lesions and periapical radiographic lucencies in cats: 265 cases (1995-1998). JAVMA 2000;217:1866-1869. 40. Miles AEW, Grigson C. Caries of the teeth. In: Colyer’s Variations and Diseases of the Teeth of Animals. New York: Cambridge University Press; 1990:476-477. 41. Restoration. In: Tutt C. Small Animal Dentistry: A Manual of Techniques. Ames, IA: Blackwell Publishing; 2006:207-209. 42. Rawlinson JE, Reiter AM. Repair of a gingival cleft associated

with a maxillary canine tooth in a dog. J Vet Dent 2005;22(4):234242. 43. Wiggs RB, Lobprise HB. Clinical oral pathology. In: Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:114-119. 44. Periodontology. In: Wiggs RB, Lobprise HB. Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven; 1997:196227. 45. Wiggs RB, Lobprise HL. Periodontal disease. In: Common Dental Procedures. Lakewood, CO: AAHA Press; 2000:45.

3 CE CREDITS

CE TEST 1

This article qualifies for 3 contact hours of continuing education credit from the Auburn University College of Veterinary Medicine. Subscribers may take individual CE tests online and get real-time scores at CompendiumVet.com. Those who wish to apply this credit to fulfill state relicensure requirements should consult their respective state authorities regarding the applicability of this program. 1. Which patient characteristic is usually best evaluated during the sedated patient examination? a. cephalic index b. anomalous teeth c. facial symmetry d. occlusion 2. Which statement regarding the cephalic index is true? a. Cephalic indices allow the veterinary dentist to assess the patient for endodontic therapy. b. The cephalic index is a measurement of the coronal width and height of the right mandibular first molar tooth. c. The cephalic index categorizes dog and cat breeds based on skull shape and size. d. The cephalic index applies to cat breeds but not to dog breeds. 3. Which statement is false with regard to dental occlusion? a. In a normal canine occlusion, the upper incisors rest on the cingulum of the lower incisors. b. In a normal canine occlusion, the upper and lower premolars interdigitate, with the lower premolars positioned rostral to the upper opposing teeth. c. The patient can be evaluated for a normal occlusion with the mouth closed. d. Traumatic malocclusions with tooth-ontooth or tooth-on-soft tissue contact can be painful for companion animals. 4. Which statement(s) regarding number of teeth is/are true? a. If teeth appear to be missing, dental radiographs are indicated.

b. Mixed dentition refers to patients having deciduous and permanent teeth. c. Adult cats normally have only one molar tooth in each dental arch. d. all of the above 5. Which breed is most likely to have CORS? a. bulldog b. whippet c. saluki d. Great Dane 6. Which statement regarding tooth color is true? a. Tooth color depends on dental care, diet, age, and other factors. b. Tooth discoloration is an indication for teeth scaling. c. Teeth normally change from yellow to white at approximately 9 to 11 years of age. d. Discolored teeth are common and rarely a reason for concern. 7. Which statement regarding diagnostic tests is true? a. Dental radiographs are useful for endodontic evaluation but not for periodontal evaluation. b. The periodontal probe is the only diagnostic test for tooth resorption. c. The periodontal probe is used for a three-dimensional assessment of the periodontium. d. Dental radiographs are rarely useful for diagnosis of tooth resorption.

8. Which statement regarding enamel defects is true? a. Enamel defects are rarely of clinical signiﬁcance. b. Enamel defects may involve only the enamel or both the enamel and the dentin. c. Enamel defects are usually inherited problems. d. Enamel defects are unlikely to be related to occlusal trauma. 9. Cage chewer syndrome refers to __________ resulting from the patient chewing metal cages. a. periodontal disease b. a pathologic condition associated with toxicity c. an enamel defect d. a combination of three problems (an enamel defect, bacterial invasion of the pulp, and endodontic and periodontal diseases) 10. Which statement is true? a. Dolichocephalic dogs are affected by periodontal disease more often than brachycephalic breeds because they have a greater incidence of dental crowding. b. A minimum width of 2 to 3 mm of attached gingiva is needed to protect the adjacent tooth. c. CUPS is not an immune-mediated condition. d. all of the above

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CE Article 2

Obstructive Lesions and Traumatic Injuries of the Canine and Feline Tracheas ❯❯ Wesley Roach, DVM The University of Georgia

❯❯ D. J. Krahwinkel, Jr., DVM, MS, DACVS, DACVA, DACVECCa University of Tennessee

At a Glance Physiology Page 86

Obstruction Page 87

Tracheal Injury Page 90

a Dr. Krahwinkel discloses that he has received financial support from Inﬁnity Medical Supplies and Intervet/Schering-Plough Animal Health.

Abstract: Tracheal obstruction and tracheal injury can be life-threatening conditions in dogs and cats. Early identiﬁcation of associated clinical signs and the use of appropriate diagnostic and therapeutic techniques are important to patient survival. Common causes of tracheal obstruction reported in the veterinary literature include tracheal foreign bodies and tracheal tumors. Tracheal injury has been associated with endotracheal intubation and external trauma. Radiography and tracheoscopy are effective diagnostic modalities, and tracheal repair or resection and anastomosis are the most common treatments.

n dogs and cats, the trachea extends Physiology from the cricoid cartilage of the larynx The trachea allows the movement of air to the carina and is composed of 35 to to and from the lower airways and the 45 and 38 to 431 rings, respectively. These removal of particulate material from the C-shaped hyaline cartilage rings are con- respiratory tree via the mucociliary escalanected to each other by fibroelastic annular tor and coughing.2,5 Ciliated epithelial cells ligaments that allow flexibility with cervi- move particulate matter and excessive cal movement. Dorsally, the rings are con- bronchial secretions toward the larynx at nected by the dorsal tracheal membrane, 12.6 mm/min.2,5,6 During a cough, the dorwhich is composed of four layers: the sal tracheal muscle contracts, decreasing mucosa, submucosa, smooth muscle fibers the tracheal lumen by 50% and increasing of the tracheal muscle, and adventitia.2,3 air velocity, which aids in removal of parThe mucosal lining of the trachea consists ticulate matter from the trachea.2 Irritation of the tracheal mucosa results of pseudostratified, ciliated columnar epithelium with basal, ciliated columnar, gob- in increased mucus secretion, inf lux of inf lammatory cells, hyperemia, and let, and nonciliated columnar cells.2 The tracheal blood supply is segmen- edema.2,6 Superficial mucosal injuries heal tal and arises from the cranial and caudal relatively quickly, with epithelial cell migrathyroid arteries and the bronchoesopha- tion occurring as early as 2 hours. Small geal artery, which form lateral vascular defects are covered with transitional epithepedicles on the sides of the trachea.2,4 lium within 48 to 72 hours, and differentiaVenous drainage is through the thyroid, tion to ciliated or goblet cells occurs within internal jugular, and bronchoesophageal 96 hours.2 Full-thickness injuries that lead to veins. Tracheal innervation is supplied gaps in the tracheal mucosa result in granuby the sympathetic nerve trunk, which lation tissue and scarring, which impairs inhibits tracheal muscle contraction and the mucociliary escalator and may cause glandular secretions. The recurrent laryn- stenosis of the tracheal lumen.2,6 However, geal nerve provides the parasympathetic up to 50% of the normal diameter of the innervation, which opposes the actions of airway lumen can be obstructed before clinical signs are evident.7,8 the sympathetic system.2

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Lesions of the Canine and Feline Tracheas CE Obstruction

Emergency Stabilization

Airway obstruction can be life threatening. It may be caused by stenosis, foreign bodies, neoplasia, torsion of the trachea, collapsed tracheal rings, granulomas, external compression, or a complication of tracheostomy.9 Reported cases of tracheal foreign bodies in dogs and cats are rare but have involved mineral oil, hair, bullets, bones, plant material, an open safety pin, and an acorn.7,10,11 Generally, when foreign bodies do enter the trachea, they are small enough to pass into the bronchial tree and cause small airway disease such as aspiration pneumonia.6 Foreign bodies that are too large to pass into the bronchi and beyond usually lodge at the carina. Primary tracheal neoplasia is uncommon in dogs and cats, with only 37 cases reported in the veterinary literature.12–l7 Of the 18 dogs reported, eight were 2 years of age or younger and diagnosed with osteochondroma or ecchondroma/osteochondromal dysplasia.13 The other 10 dogs diagnosed with primary tracheal neoplasia were 6 years of age or older, indicating a bimodal age distribution in dogs. The mean age of the 19 cats reported as having primary tracheal neoplasia was 9.5 years, with lymphoma and adenocarcinoma being the most common tumors diagnosed. Other types of primary tracheal neoplasia in cats and dogs include chondrosarcoma, mast cell tumor, squamous cell carcinoma, adenocarcinoma, osteosarcoma, extramedullary plasmacytoma, leiomyoma, and ﬁbrosarcoma.14,16,18

Patients in severe respiratory distress should be stabilized before further diagnostics are pursued. Oxygen support with a mask or nasal catheter is the mainstay of initial therapy. Sedation with acepromazine in combination with an opioid, such as butorphanol, is generally safe and effective at relieving anxiety. If swelling and edema are contributing to airway obstruction, shortacting corticosteroids, such as dexamethasone sodium phosphate at an antiinﬂammatory dose, should be administered.20 Monitoring temperature is important because animals with airway obstruction may become hyperthermic due to the increased work of breathing.21 Continuous assessment of the patient is important to determine the effectiveness of treatment. Patients that cannot be stabilized should be intubated with ventilatory support. Emergency tracheostomy may be required in patients in which intubation is unsuccessful in order to bypass the airway obstruction.20

Clinical Signs Clinical signs on presentation depend on the degree of tracheal obstruction. Patients with tracheal foreign bodies commonly present with an acute onset of coughing, inspiratory stridor, and, occasionally, rhonchi.7,19 Large tracheal foreign bodies often cause acute dyspnea and can cause cyanosis.11 Most animals with tracheal tumors present with chronic coughing, stridor, and exercise intolerance.13,14 Change in bark, dysphonia, intermittent cyanosis, collapse, or weight loss may also be noted. Cats may present with open-mouthed breathing.13 Upper airway obstruction may also precipitate pulmonary edema because of the marked negative intrathoracic pressure during the increased inspiratory effort.7

Diagnosis The patient’s condition should dictate the extent and timing of the initial diagnostic workup, with priority given to minimizing the amount of stress on the patient.6 Radiography is the initial diagnostic procedure of choice, and a lateral view of the cervical and thoracic region is generally adequate if the patient cannot tolerate dorsal or ventral recumbency.6,13 Depending on the opacity of the object, radiography may detect the presence of a foreign body within the tracheal lumen. Tracheal tumors can often be seen as soft tissue masses within the tracheal lumen on survey radiographs due to the natural negative contrast medium provided by the air within the trachea13 (FIGURE 1). Threeview thoracic radiography and regional lymph node aspiration are also important diagnostic tools for staging a suspected tracheal tumor. Obstruction in the proximal trachea results in underaeration of the lungs, a high and domed diaphragm, indrawing of the intercostal muscles or the sternum, pulmonary edema, tracheal narrowing or collapse, and distention of the pharynx.6,8 Patients with distal tracheal obstruction may have overexpanded lungs, a ﬂattened diaphragm, and prominent pulmonary vasculature secondary to air trapping caudal to the obstruction as the trachea narrows during expiration.6,13

QuickNotes Appropriate treatment for animals with tracheal injury requires recognition of respiratory distress as well as serial evaluations of clinical signs.

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FIGURE 1

Courtesy of D. J. Krahwinkel, Jr., DVM, MS, DACVS, DACVA, DACVECC

FREE CE Lesions of the Canine and Feline Tracheas

Lateral cervical radiograph with soft tissue opacity in the tracheal lumen.

Treatment The treatment for tracheal obstruction depends on the etiology of the lesion. The treatment of choice for removal of tracheal foreign bodies is endoscopy because it is minimally invasive and allows visualization of secondary injuries to the trachea.11 The small luminal diameter of puppy or cat tracheas makes endoscopic removal of some foreign bodies difficult. There is one report of a tracheal foreign body being removed by a Foley catheter technique.22 The Foley catheter is passed distal to the foreign body, and the balloon is inflated and retrieved with the foreign body. It is important to note the risks involved with this procedure, including obstructing the airway with the inflated Foley catheter balloon. The surgical options for removal of tracheal foreign bodies, tumors, and stenotic lesions are tracheotomy and tracheal resection and anastomosis, with the latter being the most common technique.

Courtesy of D. J. Krahwinkel, Jr.

Tracheoscopy allows direct visualization of the tracheal obstruction and is the method most commonly used for diagnosis of radiolucent tracheal foreign bodies10,11 (FIGURE 2). QuickNotes It also allows sampling of tracheal tumors Tracheal Resection and Anastomosis Radiography is the for cytology and histopathology, with the The surgical approach to the cervical trachea initial diagnostic former potentially providing an immediate requires the patient to be positioned in dordiagnosis.13 However, care must be used sal recumbency with the head in a relaxed modality of choice for tracheal obstruc- when anesthetizing patients with tracheal position. The skin and subcutaneous tissue foreign bodies. During tracheoscopy, inhala- are incised from the larynx to the manubrium, tion, and a lateral tion anesthesia is preferred, with the scope and the paired sternocephalicus and sterview is generally passed through the endotracheal tube. If nohyoideus muscles are separated on midline adequate if the this is not possible, then preoxygenation with blunt dissection.23 The surgical approach patient cannot toler- with intravenous anesthesia is used, with for intrathoracic tracheal resection and anastoate dorsal or ventral supplemental oxygen provided to the air- mosis is a right lateral thoracotomy between recumbency. the third to ﬁfth intercostal spaces. The adjaway through the bronchoscope.19 cent lung lobe(s) is retracted caudally or ventrally with moist sponges, the azygous vein FIGURE 2 ligated and transected, and the vagus nerve retracted.19 Once the trachea is visualized and the lateral pedicles are dissected, traction sutures are placed in the proposed proximal and distal segments of the trachea to prevent retraction after the resection and to facilitate rotation of the segments for placement of the anastomosis sutures.23 The tracheal segment containing the tumor, trauma, or stenosis is then resected. The split-ring technique (circumferentially splitting the cartilage rings and then apposing the two half rings) has been shown to result in less postoperative stenosis at the anastomosis site than the annular ligament technique (cutting through the annular ligament and anastoEndoscopic visualization of an intratracheal mass. mosing the two intact adjacent rings).24 If the

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Lesions of the Canine and Feline Tracheas CE FIGURE 3

Courtesy of D. J. Krahwinkel, Jr.

obstructed tracheal segment was preventing the endotracheal tube from passing distal to the obstruction, the endotracheal tube is now passed into the distal segment to provide positive-pressure ventilation.23 The anastomosis is performed with simple interrupted 3-0 to 5-0 monoﬁlament nonabsorbable sutures.19,23 The sutures go through the split cartilages and may enter the tracheal lumen. The endotracheal tube is withdrawn proximal to the anastomosis, and the site is submerged in saline as positive-pressure ventilation is applied to check for leaks and the need for additional sutures. Muscle or mediastinal tissues are closed over the trachea, and the surgical site is closed routinely. A thoracostomy tube is placed to evacuate the pleural space if a thoracotomy was required.19 Few short- and long-term complications have been associated with tracheal resection and anastomosis. 25 However, anastomotic stenosis is a signiﬁcant complication associated with excessive tension or poor alignment at the anastomosis site. If too many tracheal rings are removed, the tension at the anastomosis site will exceed the suture-holding strength of the cartilaginous tissue, leading to dehiscence and stenosis of the tracheal ends.19 The amount of trachea that can be safely resected without excessive tension on the anastomosis site varies with patient age. It has been reported that only three to 10 tracheal rings in puppies 6 to 8 weeks of age, and fewer than 14 tracheal rings in puppies 12 to 18 weeks of age, can be safely removed without excessive tension at the anastomosis site. This is in comparison to the reported eight to 23 tracheal rings that can be removed in an adult dog. The tracheas of younger animals are more elastic, containing less collagen and more water than the adult trachea, making them more susceptible to tension. Separation, which occurs at the anastomosis site as the tension increases, heals with granulation tissue, resulting in varying degrees of tracheal stenosis.19 Tension is greatest near the anastomosis site because fascial and vessel attachments prevent the tension from being dispersed over the entire tracheal length. Therefore, freeing the trachea from these attachments both cranially and caudally to the resection site allows anastomosis under less tension. However, dissection of the trachea should be limited to avoid

Completed tracheal resection and anastomosis using a simple interrupted suture pattern and tension sutures.

disrupting the segmental blood supply.4 Also, using tension sutures that encircle a tracheal ring two to three rings from the anastomosis in the proximal and distal segments helps relieve tension on the primary suture line.19 Maintaining cervical flexion with a martingale-style neck brace during the first 2 weeks postoperatively also decreases the number of stress points that can lead to dehiscence.19,26 Accurate mucosal alignment at the anastomosis site is important because mucosal defects may lead to formation of granulation tissue and possible stenosis.19 Tracheal anastomosis using monofilament nonabsorbable sutures in a simple interrupted pattern is preferred because simple continuous suture patterns have been associated with less precise apposition and greater luminal stenosis14,23,25 (FIGURE 3). Penetrating the cartilaginous rings with the suture needle is indicated in all but young, small, or old animals. Older animals may have mineralized tracheal rings that can fracture, and younger animals have less rigid tracheal rings that may tear when penetrated by a needle. Using a fine cutting needle reduces this risk. Otherwise, tracheal ring–encircling sutures can be used in these cases, although this technique has been associated with overriding or telescoping of the anastomosed rings.19 During tracheal resection and anastomosis, it is also important to visualize and protect the recurrent laryngeal nerves to avoid iatrogenic laryngeal paralysis.25 Perioperative broad-spectrum antibiotics are administered because the surgery is performed

QuickNotes Tracheal lacerations can be repaired with simple suture techniques.

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FREE CE Lesions of the Canine and Feline Tracheas

in a contaminated airway. Postoperatively, sedation and conﬁnement are used to lessen the chances of trachea dehiscence. Providing supplemental oxygen and careful monitoring is also important. Postoperative evaluation should include survey lateral thoracic radiographs and tracheoscopy at 2 to 3 months to monitor for tracheal stenosis.25

Other Options In addition to the tracheal resection and anastomosis described above, treatment options for tracheal tumors include surgical excision, chemotherapy, radiation therapy, or a combination of these.13 There are reports of surgical excision by blunt dissection15,16 and endoscopic snaring.13,14,17 Staging the disease before deﬁnitive treatment is recommended; however, tracheal neoplasia causing respiratory compromise is an indication for immediate intervention.13

Prognosis

QuickNotes Many tumors can be managed by tracheal resection and anastomosis.

The short-term prognosis after surgical excision of tracheal tumors is favorable.13 However, long-term follow-up has been conducted for few canine and feline primary tracheal tumors after surgical resection. Osteocartilaginous tracheal tumors in young dogs with active osteochondral ossiﬁcation are usually benign and do not recur once the patient has reached skeletal maturity.13,14 Therefore, complete resection of benign tumors of the trachea, such as benign osteochondral tumors, have a good prognosis because excision is usually curative.14,16 Malignant tracheal tumors have a guarded prognosis, and advanced lesions may not be surgically resectable.14 Incompletely excised tumors may require adjunctive treatment.16 Palliative intraluminal stenting may provide temporary relief for unresectable neoplasms causing tracheal obstruction.27 Feline tracheal lymphoma may respond to radiation, systemic chemotherapy, or a combination of both. Overall, prognosis with primary tracheal neoplasia in dogs and cats depends on the tumor type and stage and the degree of respiratory compromise.6,13

Tracheal Injury Tracheal injury can be caused by intraluminal or external trauma. The former is associated with endotracheal intubation, while the latter

is most commonly seen secondary to a dog fight or automobile accident.28-30 Tracheal injuries can range from small lacerations to tracheal avulsions. The dorsal tracheal membrane is protected dorsally by the cervical spine, laterally by the neck musculature, and ventrally by the tracheal rings.31 Disruption of the dorsal tracheal membrane is most commonly a result of intraluminal tracheal damage, such as from overzealous endotracheal intubation, overinflation of the endotracheal tube cuff, inappropriate use of a stylet in an endotracheal tube during intubation, a change in head position without disconnecting the endotracheal tube, or removal of the endotracheal tube without deflating the cuff. These tracheal ruptures are commonly located at the dorsolateral junction of the tracheal rings and trachealis muscle at the thoracic inlet and are 2 to 5 cm long (corresponding to the length of an endotracheal tube cuff).29 However, there is one report of a pericarinal tracheal laceration produced during tracheal intubation of a cat.32 Tracheal rupture associated with endotracheal intubation has been well documented in cats.19,29,30 One review determined that the volume of air needed to obtain an airtight seal in a feline endotracheal tube was 0.9 to 2.3 mL and that inflating the cuff with more air increased the risk of tracheal rupture.30 To avoid iatrogenic tracheal rupture, it is essential that endotracheal tube cuffs be inflated to effect and not with an arbitrary amount of air. Several studies have attempted to determine which types of endotracheal tubes are most likely to cause tracheal rupture.29,33 Low-pressure endotracheal tube cuffs should be safer to use than high-pressure cuffs. However, it appears that proper use of endotracheal tubes and cuff inflation is more important than which type of endotracheal tube is used.29,30 The intrathoracic trachea is protected by the thoracic wall; therefore, rupture from external trauma is most likely a result of luminal and longitudinal traction.25 Intrathoracic tracheal avulsion in cats has been well documented and is caused by a sudden, dramatic increase in intratracheal luminal pressure during impact with the glottis closed or with blunt trauma that causes whiplash extension of the neck. The carinal region is a fixed point and is stronger than the tracheal wall, which makes the trachea more prone to tearing cranial to the carina.28

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Lesions of the Canine and Feline Tracheas CE Clinical Signs

Courtesy of D. J. Krahwinkel, Jr.

FIGURE 4

Tracheal injuries characteristically result in subcutaneous emphysema over the cervical and thoracic areas due to air escaping from the trachea into the subcutaneous tissue.6,29,34 Patients that present in respiratory distress due to a compromised upper airway develop dyspnea, mild to moderate increases in respiratory and heart rates, and inspiratory stridor with a prolonged inspiratory phase followed by a variable expiratory phase.8 Other clinical signs include coughing, exercise intolerance, gagging, exertional distress, fever, and cyanosis.11,30,35 Dyspnea can also be caused by restrictive respiratory diseases, such as pneumothorax, which can be concurrent with tracheal injuries. Trauma is a primary cause of tracheal injury; therefore, it is important to evaluate the entire patient for other problems. Injuries of the cervical trachea due to external injury may or may not have overlying skin lacerations. Tracheal avulsion injuries in cats produce two distinct clinical presentations. One is acute onset of dyspnea and respiratory compromise. The second is a more chronic onset of dyspnea, exercise intolerance, and exertional respiratory distress days to weeks after the traumatic episode, caused by severe circumferential luminal stenosis of the proximal and distal ends of the avulsed trachea.35 In one report of seven cats presented for respiratory signs with a known history of trauma, only one cat presented within 24 hours of the traumatic episode. The other six cats presented 1 to 3 weeks after the injury. In another report of 16 cats with intrathoracic tracheal avulsion, most cats had no obvious respiratory signs at the time of the traumatic episode.36 Onset of dyspnea in these cases ranged from 1 to 28 days, with a median of 12.5 days. In chronic cases, the airway lumen is maintained after the avulsion injury by either intact tracheal adventitia or thickening of the mediastinal tissue leading to development of a pseudotrachea that provides continuity of the airway.25 However, granulation and scar tissue eventually narrow the lumen at both ends of the tracheal avulsion25,28 (FIGURE 4). Patients may develop anorexia, open-mouthed breathing, cyanosis, and marked inspiratory and expiratory effort with progression to suffocation as the free ends of the trachea narrow.28

Tracheal rupture with avulsion and granulation tissue causing stenosis of the tracheal lumen.

Diagnosis Radiography can be used to identify changes consistent with tracheal injury. Radiographs of the cervical region typically show subcutaneous emphysema but may not display an obvious disruption of the trachea. In a study of 20 cats with tracheal rupture associated with intubation, radiographs showed pneumomediastinum and subcutaneous emphysema in all the cats.29 Thoracic radiographs of an animal with an acute tracheal avulsion may show a pneumomediastinum because air is leaking from the tracheal rupture and dissecting along muscles into the thoracic inlet.28,34 If a pseudotrachea is maintained, radiographs may reveal loss of continuity of the thoracic trachea, with a gas-ﬁlled diverticulum between the separated tracheal rings.36 The tracheal lumen may be obscured by a soft tissue opacity if there is stenosis at each end.28 Tracheoscopy can also aid in diagnosing tracheal injury by providing direct visualization of the lesion (FIGURE 5). In one review of tracheal rupture due to endotracheal intubation, tracheoscopy was the diagnostic method of choice.30 However, in another study, tracheoscopy did not detect tracheal rupture associated with endotracheal intubation in two cats that was later conﬁrmed at surgery.29 As mentioned previously, it is important to realize the risks associated with anesthesia and tracheoscopy in critical respiratory patients.

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Lesions of the Canine and Feline Tracheas

Courtesy of D. J. Krahwinkel, Jr.

FIGURE 5

Endoscopic visualization of a dorsal tracheal membrane lesion.

Treatment Tracheal injuries can be treated with supportive medical care or surgical intervention, depending on the clinical status of the animal, the extent of the tracheal damage, and the cause of the tracheal disruption. Appropriate monitoring for tracheal injury requires serial evaluations of respiratory status and progression of subcutaneous emphysema.29 Most cats with tracheal injury associated with intubation showing mild to moderate signs of dyspnea and subcutaneous emphysema can be treated medically. Subcutaneous emphysema can take 1 to 6 weeks to resolve, with a median of 2 weeks. If signiﬁcant secondary stenosis occurs following medical management of a tracheal injury, surgery is indicated to avoid worsening of the stenosis and inevitable progression to death. Dogs and cats with severe dyspnea should be evaluated and treated for pneumothorax before being considered for surgery. Patients with continued dyspnea or worsening subcu-

taneous emphysema should be treated with immediate surgical intervention. 29 Caution should be used when anesthetizing critical patients with tracheal injuries. Smaller patients should be placed in an induction box and preoxygenated before the anesthesia is added. When the patient is intubated, the endotracheal tube should not pass beyond the tracheal lesion. Positive-pressure respiration is also avoided to prevent rupture of the airway.19 The trachea is approached gently to avoid damage to the tracheal blood supply and recurrent laryngeal nerves, using the surgical approaches to the cervical or thoracic trachea described for the treatment of tracheal obstruction. The injured site may not be evident but can be located by filling the surgical field with saline and applying positive-pressure ventilation. Bubbles will appear at the location of the injury. The trachea is repaired by direct suturing. If the tracheal wound is irregular, then debridement of the edges should precede suturing. Ruptured dorsal tracheal membranes have been repaired with various suture patterns, including simple interrupted or continuous patterns. In one case report, an airtight seal was obtained with a horizontal mattress pattern that was oversewn with a simple continuous pattern.31 Tracheal resection and anastomosis is the only effective treatment for stenosis of an avulsed trachea in cats.28 Once the tracheal lesion is resected, the endotracheal tube is passed into the distal trachea with the surgeon’s guidance.19 Perioperative antibiotics are administered to prevent contamination from the injury or the airway. Drains are often placed due to the contamination of the surgical site and to prevent the formation of seromas. Any subcutaneous emphysema is absorbed over several days to weeks. Postoperative care includes confinement and sedation to avoid disrupting the surgical repair.

References 1. Light GS. Respiratory system. In: Hudson LC, Hamilton WP, eds. Atlas of Feline Anatomy for Veterinarians. Philadelphia: WB Saunders; 1993:137-148. 2. Colley P, Henderson R, Huber M. Tracheostomy techniques and management. Compend Contin Educ Pract Vet 1999;21(1):44-53. 3. Evans HE. The respiratory system. In: Evans HE, ed. Miller’s Anatomy of the Dog. 3rd ed. Philadelphia: WB Saunders; 1993:479-480. 4. Orton EC. Small Animal Thoracic Surgery. Baltimore: Williams and Wilkins; 1995. 5. Bojrab MJ, Nate LL. Tracheal reconstructive surgery. JAAHA 1976;12:622-628. 6. Ettinger SJ, Kantrowitz B. Diseases of the trachea. In: Ettinger

SJ, Feldman EC, eds. Textbook of Veterinary Internal Medicine. 6th ed. St. Louis: Elsevier Saunders; 2005:1217-1232. 7. Dimski DS. Tracheal obstruction caused by tree needles in a cat. JAVMA 1991;199(4):477-478. 8. Sadler VM, Wisner ER. What is your diagnosis? Circumferential foreign body within the soft tissues of the neck and pronounced tracheal compression. JAVMA 2000;216(11):1723-1724. 9. Smith MM, Gourley IM, Arnis TC, Kurpershoek C. Management of tracheal stenosis in a dog. JAVMA 1990;196(6):931-934. 10. Jones BD, Roudebush P. The use of ﬁberoptic endoscopy in the diagnosis and treatment of tracheobronchial foreign bodies. JAAHA 1984;20:497-504.

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

Lesions of the Canine and Feline Tracheas 11. Nawrocki MA, Mackin AJ, Cantwell HD, Ellis B. What is your diagnosis? Spherical soft tissue opacity in the area of the distal portion of the trachea. JAVMA 2002;221(6):783-784. 12. Aron DN, DeVries R, Short CE. Primary tracheal chondrosarcoma in a dog: a case report with description of surgical and anesthetic techniques. JAAHA 1980;16:31-37. 13. Brown MR, Rogers KS. Primary tracheal tumors in dogs and cats. Compend Contin Educ Pract Vet 2003;25(11):854-860. 14. Greenfield CL. Respiratory tract neoplasia. In: Slatter D, ed. Textbook of Small Animal Surgery. 3rd ed. Philadelphia: Saunders; 2003:2474-2487. 15. Hough JD, Krahwinkel DJ, Evans AT, et al. Tracheal osteochondroma in a dog. JAVMA 1977;170(12):1416-1418. 16. Weigt AK, McCracken MD, Krahwinkel DJ. Extramedullary plasmacytoma in the canine trachea: case report and literature review. Compend Contin Educ Pract Vet 2001;23(2):143-152. 17. Withrow SJ, Holmberg DL, Rosychuk RA, et al. Treatment of a tracheal osteochondroma with an overlapping end-to-end tracheal anastomosis. JAAHA 1978;14(4):469-473. 18. Mahler SP, Mootoo NF, Reece JL, Cooper JE. Surgical resection of a primary tracheal fibrosarcoma in a dog. J Small Anim Pract 2006;47(9):537-540. 19. Nelson AW. Diseases of the trachea and bronchi. In: Slatter D, ed. Textbook of Small Animal Surgery. 3rd ed. Philadelphia: Saunders; 2003:858-880. 20. Reiss AJ, McKiernan BC. Laryngeal and tracheal disorders. In: Wingfield WE, Raffe MR, eds. The Veterinary ICU Book. Jackson Hole, Wyoming: Teton NewMedia; 2002:605-615. 21. Perkowski S. Respiratory system. In: Slatter D, ed. Textbook of Small Animal Surgery. 3rd ed. Philadelphia: Saunders; 2003:25642572. 22. Pratschke KM, Hughes JM, Guerin SR, Bellenger CR. Foley catheter technique for removal of a tracheal foreign body in a cat. Vet Rec 1999;144(7):181-182. 23. Fingland RB, Layton CI, Kennedy GA, Galland JC. A compari-

son of simple continuous versus simple interrupted suture patterns for tracheal anastomosis after large-segment tracheal resection in dogs. Vet Surg 1995;24:320-330. 24. Hedlund CS. Tracheal anastomosis in the dog: comparison of two end-to-end techniques. Vet Surg 1984;13(3):135-142. 25. White RN, Burton CA. Surgical management of intrathoracic tracheal avulsion in cats: long-term results in 9 consecutive cases. Vet Surg 2000;29:430-435. 26. Hauptman J, White JV, Slocombe RF. Intrathoracic tracheal stricture management in a dog. JAAHA 1985;21:505-510. 27. Weiss C, Berent A, Todd K, et al. Evaluation of palliative stenting for management of malignant urethral obstructions in dogs. JAVMA 2006;229(2):226-234. 28. Miles JE. What is your diagnosis? Tracheal rupture. J Small Anim Pract 1999;40(8):357, 398. 29. Mitchell SL, McCarthy R, Rudloff E, Pernell RT. Tracheal rupture associated with intubation in cats: 20 cases (1996-1998). JAVMA 2000;216(10):1592-1595. 30. Hardie EM, Spodnick GJ, Gilson SD, et al. Tracheal rupture in cats: 16 cases (1983-1998). JAVMA 1999;214(4):508-512. 31. Clements DN, McGill S, Beths T, Sullivan M. Tracheal perforation secondary to suture irritation in a dog following a ventral slot procedure. J Small Anim Pract 2003;44(7):313-315. 32. Kastner SB, Grundmann S, Bettschart-Wolfensberger R. Unstable endobronchial intubation in a cat undergoing tracheal laceration repair. Vet Anaesth Analg 2004;31(3):227-230. 33. Nishiyama T. Comparison of the intracuff pressures of three different tracheostomy tubes. J Anesth 2005;19(3):260-262. 34. Caylor KB, Moore RW. What is your diagnosis? Severed cervical trachea and substantial subcutaneous emphysema in a cat. JAVMA 1994;205(4):561-562. 35. White RN, Milner HR. Intrathoracic tracheal avulsion in three cats. J Small Anim Pract 1995;36(8):343-347. 36. Lawrence DT, Lang J, Culvenor J, et al. Intrathoracic tracheal rupture. J Feline Med Surg 1999;1(1):43-51.

3 CE CREDITS

CE TEST 2

5. The number of tracheal rings that can be safely removed during resection and anastomosis in a 6- to 8-week-old puppy is a. <10. b. 12. c. 14. d. >16.

8. After traumatic tracheal avulsion, cats may show no signiﬁcant respiratory compromise if the _________ is/are intact. a. tracheal adventitia b. sternohyoideus muscles c. sternocephalicus muscles d. skin

6. Tracheal rupture in cats is most commonly associated with a. gunshot wounds. b. coughing. c. esophageal rupture. d. endotracheal intubation.

9. Animals with suspected tracheal rupture should go immediately to surgery if subcutaneous emphysema is a. unchanging. b. resolving. c. worsening. d. absent.

7. _________ is a common clinical sign of tracheal rupture. a. Hemoptysis b. Subcutaneous emphysema c. Inspiratory stridor d. Head tilt

10. _________ is/are the only effective treatment for stenosis of avulsed tracheal ends. a. Cage rest b. Bronchodilators c. Cough suppressants d. Tracheal resection and anastomosis

CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

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CompendiumVet.com | February 2009 | Compendium: Continuing Education for Veterinarians®

Table 2: Number of Dogs* with Adverse Reactions Reported During the Field Study with CONVENIA.

(cefovecin sodium) Antimicrobial for Subcutaneous Injection in Dogs and Cats Only CAUTION: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: Dogs CONVENIA is indicated for the treatment of skin infections (secondary superficial pyoderma, abscesses, and wounds) in dogs caused by susceptible strains of Staphylococcus intermedius and Streptococcus canis (Group G). Cats CONVENIA is indicated for the treatment of skin infections (wounds and abscesses) in cats caused by susceptible strains of Pasteurella multocida. CONTRAINDICATIONS: CONVENIA is contraindicated in dogs and cats with known allergy to cefovecin or to B-lactam (penicillins and cephalosporins) group antimicrobials. Anaphylaxis has been reported with the use of this product in foreign market experience. If an allergic reaction or anaphylaxis occurs, CONVENIA should not be administered again and appropriate therapy should be instituted. Anaphylaxis may require treatment with epinephrine and other emergency measures, including oxygen, intravenous fluids, intravenous antihistamine, corticosteroids, and airway management, as clinically indicated. Adverse reactions may require prolonged treatment due to the prolonged systemic drug clearance (65 days). WARNINGS: Not for use in humans. Keep this and all drugs out of reach of children. Consult a physician in case of accidental human exposure. For subcutaneous use in dogs and cats only. Antimicrobial drugs, including penicillins and cephalosporins, can cause allergic reactions in sensitized individuals. To minimize the possibility of allergic reactions, those handling such antimicrobials, including cefovecin, are advised to avoid direct contact of the product with the skin and mucous membranes. PRECAUTIONS: Prescribing antibacterial drugs in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to treated animals and may increase the risk of the development of drug-resistant animal pathogens. The safe use of CONVENIA in dogs or cats less than 4 months of age (see Animal Safety) and in breeding or lactating animals has not been determined. Safety has not been established for IM or IV administration. The long-term effects on injection sites have not been determined. CONVENIA is slowly eliminated from the body, approximately 65 days is needed to eliminate 97% of the administered dose from the body. Animals experiencing an adverse reaction may need to be monitored for this duration. CONVENIA has been shown in an experimental in vitro system to result in an increase in free concentrations of carprofen, furosemide, doxycycline, and ketoconazole. Concurrent use of these or other drugs that have a high degree of protein-binding (e.g. NSAIDs, propofol, cardiac, anticonvulsant, and behavioral medications) may compete with cefovecin-binding and cause adverse reactions. Positive direct Coombs’ test results and false positive reactions for glucose in the urine have been reported during treatment with some cephalosporin antimicrobials. Cephalosporin antimicrobials may also cause falsely elevated urine protein determinations. Some antimicrobials, including cephalosporins, can cause lowered albumin values due to interference with certain testing methods. Occasionally, cephalosporins and NSAIDs have been associated with myelotoxicity, thereby creating a toxic neutropenia1. Other hematological reactions seen with cephalosporins include neutropenia, anemia, hypoprothrombinemia, thrombocytopenia, prolonged prothrombin time (PT) and partial thromboplastin time (PTT), platelet dysfunction and transient increases in serum aminotransferases. ADVERSE REACTIONS: Dogs A total of 320 dogs, ranging in age from 8 weeks to 19 years, were included in a field study safety analysis. Adverse reactions reported in dogs treated with CONVENIA and the active control are summarized in Table 2.

Active Control (n=163) Lethargy 2 7 Anorexia/Decreased Appetite 5 8 Vomiting 6 12 Diarrhea 6 7 Blood in Feces 1 2 Dehydration 0 1 Flatulence 1 0 Increased Borborygmi 1 0 *Some dogs may have experienced more than one adverse reaction or more than one occurrence of the same adverse reaction during the study. Mild to moderate elevations in serum G-glutamyl transferase or serum alanine aminotransferase were noted post-treatment in several of the CONVENIA-treated dogs. No clinical abnormalities were noted with these ﬁndings. One CONVENIA-treated dog in a separate ﬁeld study experienced diarrhea post-treatment lasting 4 weeks. The diarrhea resolved. Adverse Reaction

Online Forms Canine and Feline Dental Exam Forms

CONVENIA (n=157)

Cats A total of 291 cats, ranging in age from 2.4 months (1 cat) to 21 years, were included in the field study safety analysis. Adverse reactions reported in cats treated with CONVENIA and the active control are summarized in Table 3. Table 3: Number of Cats* with Adverse Reactions Reported During the Field Study with CONVENIA. Active CONVENIA Control (n=147) (n=144) Vomiting 10 14 Diarrhea 7 26 Anorexia/Decreased Appetite 6 6 Lethargy 6 6 Hyper/Acting Strange 1 1 Inappropriate Urination 1 0 *Some cats may have experienced more than one adverse reaction or more than one occurrence of the same adverse reaction during the study. Four CONVENIA cases had mildly elevated post-study ALT (1 case was elevated pre-study). No clinical abnormalities were noted with these findings. Twenty-four CONVENIA cases had normal pre-study BUN values and elevated post-study BUN values (37 – 39 mg/dL post-study). There were 6 CONVENIA cases with normal pre- and mildly to moderately elevated post-study creatinine values. Two of these cases also had an elevated post-study BUN. No clinical abnormalities were noted with these findings. One CONVENIA-treated cat in a separate field study experienced diarrhea post-treatment lasting 42 days. The diarrhea resolved.

These downloadable forms can be used to gather important information about a patient’s dental visit. They include dental charts, an abbreviation index, and space to note treatment options. Examination 109

108

107

106

104 103 102 101 201 202 203 204

205

207

208

209

I2 I1 1I 2I 3I

Buccal Occlusal Palatal

Decid. D 500

600

800

700

Adverse Reaction

FOREIGN MARKET EXPERIENCE: The following adverse events were reported voluntarily during post-approval use of the product in dogs and cats in foreign markets: death, tremors/ataxia, seizures, anaphylaxis, acute pulmonary edema, facial edema, injection site reactions (alopecia, scabs, necrosis, and erythema), hemolytic anemia, salivation, pruritus, lethargy, vomiting, diarrhea, and inappetance. For a copy of the Material Safety Data Sheet (MSDS) or to report a suspected adverse reaction call Pﬁzer Animal Health at 1-800-366-5288.

Occlusal Buccal

409

408

407

404

403 402 401 301 302 303

304

307

308

309

Each form contains exam and treatment charts that use two tooth identiﬁcation systems. See the article “Oral Examination of Cats and Dogs,” which starts on page 72, for an explanation of these systems. Visit CompendiumVet.com to download the forms. ATION TAL EXAMIN FELINE DEN ENT

OTHER

3 Rads: 1 2

TREATM

Examination 109

108

107

106

201 202 203 204 104 103 102 101 1C I1 1I 2I 3I C1 I3 I2

207

208

209

205

Scaling Polishing Extraction Comments: Buccal Occlusal Palatal 600

700

Decid.

Lingual

500 800

Occlusal Buccal

STORAGE INFORMATION: Store the powder and the reconstituted product in the original carton, refrigerated at 2o to 8o C (36o to 46o F). Use the entire contents of the vial within 28 days of reconstitution. PROTECT FROM LIGHT. After each use it is important to return the unused portion back to the refrigerator in the original carton. As with other cephalosporins, the color of the solution may vary from clear to amber at reconstitution and may darken over time. If stored as recommended, solution color does not adversely affect potency.

408

407

404

409

1I 2I 3I I3 I2 I1 301 302 303 403 402 401

304

307

308

1M 309

Treatment 108

107

106

109

(months ago):

Last prophy Home care:

201 202 203 204 104 103 102 101 1C I1 1I 2I 3I C1 I3 I2

205

207

208

209 1M

110 M2

l107 108 Occlusa

109 M1

Palatal 600 700

Decid.

106 P2

105 104 l facial 103 102 101 201 202 Extraora 203 204 P1 C1 205 206 I3 I2 I1 207 1I 2I 3I 1C nodes 208 Lymph 1P 2P 3P 4P

l Buccal mucosa

N-A 209 1M

Occlusal

Decid. De 800

Bucccal Bucc -A N al

Palate

500

Buccal

408

407

404

409

1I 2I 3I I3 I2 I1 301 302 303 403 402 401

Pala Palat latal alN - A

M2 410

M1 409

N-A

Ling Lingu nguaall

Buc Bucc ccal al

P1 C1 I3 I2 I1 408 407 1I 2I 3I 406 405 1C 1P 2P 404 403 3P 4P 402 401 301 302 303 304 305 306 307 308

1M 2M 3M PE Pulp exposed 309 index (1, 2, 3)310 311 Granuloma PI Plaque (1, 2, 3) ntal pocket Gingival index PP Periodo Treatm ent l hyperplasia ntal prophylaxis GH Gingiva PRO Periodo 110 109 n l108recessio 107 106 site ﬁlling GR M2Gingiva Compo 105 104 R/C M1 P4 2, 3) 103 102 101 201 202 203 204 P3 (1, us P2 P1 index 205 206 d deciduo C1 I3 MI Mobility Retaine I2 I1 1I RD 207 208 2I 3I 209 1C 1P 2P 3Pd root tip 210 OM Oral mass RRT Retaine 4P 1M 2M PC Pulp capping

Abbreviations

700

Occ Occlu clusa sall M3 411

600

Salivary ﬂow

309

308

307

304

al Biopsy, excision al Biopsy, incision Caries

(1, 2, 3) Calculus index ion CR Crown restorat 3) n index (1, 2, FI Furcatio d tooth or jaw FX Fracture

itis ST Stomat T/A Tooth avulsed d T/I Tooth impacte on (1, 2, 3, 4) TR Tooth resorpti extraction Simple closed X with gical extraction XS Nonsur ng tooth sectioni l extraction XSS Surgica Last

Home care:

Bucccal Bucc al

Decid. De

500

Occcl Occlu clusa sal all

800

Brush:

Oral rinse :

P Palat ala latal al

REFERENCES: 1 Birchard SJ, Sherding RG. Saunders manual of small animal practice. 2nd ed. Philadelphia: PA: WB Saunders Co, 2000;166.

600 700

Ling Lingu nguaall Occlusal M3 411

M2 410

M1 409

P4 P3 P2 P1 C1 I3 I2 I1 1I 408 407 2I 3I 1C 406 405 1P 2P 404 403 402 3P 4P 401 301 302 303 304 305 306 307 308

Buccal 2M 310

Biopsy, excisional Biopsy, incisional Caries Calculus index (1, 2, 3) CR Crow n restoratio n FI Furc ation index (1, 2, 3) FX Fract ured tooth or jaw

January 2008 820 038 000 692432

Material: Habits: N-A N-A N-A N-A N-A

N-A

Pharynx Salivary ﬂow

Material: N

Diet / Oral

B Buccal mucosal

Tonsils

311

N Y

Tongue Palate

1M 309

Abbrevia tions

NADA# 141-285, Approved by FDA

Extraoral facial Lymph nodes

N-A N-A

G Gran uloma GI Ging ival index (1, 2, 3) GH Ging ival hype rplasia GR Ging ival reces sion MI Mob ility index (1, 2, 3) OM Oral mass PC

Pulp capp ing

Pulp expo sed PI Plaq ue index (1, 2, 3) PP Perio dontal pock et PRO Perio dontal prop hylaxis R/C Com posite ﬁ lling RD Reta ined decid uous RRT Reta ined root tip

Compendium | February 2009

CompendiumVet.com

OTHER Rads: 1 2 3

Occclusa Occlu -l A Nsal

Tonsils Pharynx

Scaling Polishing Extraction Comment s:

N-A N-A

Tongue

800

TREATME NT

210 2M

Lingual

500

HOW SUPPLIED: CONVENIA is available as a 10 mL multi-use vial containing 800 milligrams of cefovecin as a lyophilized cake.

Material:

CA Brush: NINE Material: N NT Y DE TAL EX ExaminatOral rinse: AMINA ion Diet / Oral Habits: AT TIIO ON N N-A Y

Buccal

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Now thereâ&#x20AC;&#x2122;s CONVENIA. The ďŹ rst antibiotic to provide an assured course of treatment in one professionally administered injection.

s CONVENIAÂŽ (cefovecin sodium) is an injectable cephalosporin antibiotic indicated for the treatment of most routine skin infections in dogs and cats. s A single injection of CONVENIA provides up to 14 days of antibiotic treatment,* completely eliminating the need for daily oral antibiotics. s CONVENIA delivers the safety and efďŹ cacy you expect from a cephalosporin. s More than 6 million pets have been treated globally with CONVENIA since 2006. s CONVENIA puts you in control of dosing and administration. *In clinical studies, a single injection of CONVENIA was clinically equivalent to a 14-day antibiotic regimen. CONVENIA is not for use in dogs or cats with a history of allergic reactions to penicillins or cephalosporins. Similar to other cephalosporins, side effects for both dogs and cats include vomiting, diarrhea, decreased appetite/anorexia and lethargy. The safety of CONVENIA has not been determined in lactating or breeding animals. See page 96 for product information summary.

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Cat owners listen to their cats. Listen to your cat owners. Cats and their owners agree: a topical dewormer beats a pill any day. In fact, nearly 90% of cat owners prefer topical drops to pills or tablets.* So listen to your cat owners. Choose the only feline dewormer that treats and controls roundworms, hookworms and tapeworms with the ease and convenience of a topical application: ProfenderÂŽ Topical Solution. *From a survey of 736 cat owners. Data on file.

Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian. Children should not contact application site for twenty-four (24) hours.

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See Page 94 for Product Information Summary