The Modern Equine Vet December 2018 by The Modern Equine Vet

The Modern

Equine Vet www.modernequinevet.com

Laminitis Pain Treatment in the ambulatory setting

Ketamine Dose for Minor Field Surgery Gram-Negatives Prove Lethal Anesthesia in Mules, Miniatures and Hybrids

Vol 8 Issue 12 2018

TABLE OF CONTENTS

COVER STORY

Drugs and Commitment:

4 Treating Laminitis

Pain in Ambulatory Practice Cover photo: Shutterstock/Erik Kunddahl

INFECTIOUS DISEASES

Gram-Negatives Prove Lethal in Equine Joint Infections.................................................10 ANESTHESIOLOGY

Horses of a Different Color.........................................................................................................16 NEWS

Ketamine Dose Affects Minor Surgical Conditions and Recovery................................... 3 Magnesium May Not Be a Calming Influence......................................................................14 Luitpold Becomes American Regent Animal Health .........................................................17 TRH Stimulation Test Best for PPID in Donkeys ..................................................................18 Merck Animal Health/AAEP Foundation Scholarship Awarded to 5 Promising Equine Veterinary Students.......................................................18 BI Announces Winners of 2018 Champions of the Cause Awards.................................18 ADVERTISERS Shanks Veterinary Equipment..................................3 Luitpold Animal Health..............................................5 Purina Animal Nutrition.............................................7 Avalon Medical.............................................................8

Standlee Premium Western Forage.........................9 Boehringer Ingelheim/Equioxx..............................11 Boehringer Ingelheim/Vetera................................13 Merck Animal Health................................................15

The Modern

Equine Vet SALES: Matthew Todd • ModernEquineVet@gmail.com Lillie Collett • ModernEquineVetSales@gmail.com EDITOR: Marie Rosenthal • mrosenthal@percybo.com ART DIRECTOR: Jennifer Barlow • jbarlow@percybo.com CONTRIBUTING WRITERS: Paul Basillo • Carol Jean Ellis Jason Mazda • Adam Marcus COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers PERCYBO media  publishing

Issue 12/2018 | ModernEquineVet.com

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NEWS NOTES

Ketamine Dose Affects Minor Surgical Conditions and Recovery

Horses that received the higher dose of ketamine became relaxed more quickly after induction, and surgical conditions were better.

Shutterstock/kiep

A higher dose of IV ketamine may result in better surgical conditions than a lower dose, but appears to adversely affect recovery quality for field surgery, according to new research. Ketamine is frequently the anesthesia of choice for field surgeries, and researchers wanted to know if the dosing affected surgical conditions and recovery. In this prospective, randomized, blinded study, Hulda Harðardóttir and colleagues in the United Kingdom and Iceland compared 2 doses of ketamine (2.2 mg/kg and 5 mg/kg IV) for induction of anesthesia in 77 Icelandic horses undergoing field castration.

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Prior to induction, the horses were sedated with xylazine (0.7 mg/kg), butorphanol (25 μg/kg) and acepromazine (50 μg/kg) IV, and sedation quality was assessed 5 minutes later. Horses were allocated randomly 1 of the 2 ketamine doses and induced with IV ketamine and diazepam (30 μg/kg). Induction quality, surgical conditions and recovery were assessed using subjective and objective measures. Horses that received the higher dose of ketamine became relaxed more quickly after induction, and surgical conditions were better; however, recovery quality was subjectively worse, but no adverse events were observed. Five horses that received the lower dose of ketamine required additional ketamine doses during anesthesia compared with only 2 that received the higher dose. MeV

For more information: Harðardóttir H, Murison PJ, Blissitt K, et al. A comparison of two ketamine doses for field anesthesia in horses undergoing castration. Equine Vet J 2018 Nov. 24 [Epub ahead of print]). https://onlinelibrary.wiley.com/doi/pdf/10.1111/evj.13052

www.shanksvet.com • info@shanksvet.com ModernEquineVet.com | Issue 12/2018

LAMINITIS

Drugs and Commitment:

Few things in equine practice are more frustrating than laminitis. Too often, owners do not have the resources or commitment to adequately manage these horses, so they present too late in the process for aggressive treatment. “You need to be aggressive in the [acute phase] of laminitis to prevent more damage and to get on top of the pain,” said Lori A Bidwell, DVM, DACVAA, here at the 64th Annual AAEP Convention in San Francisco. “There is a lot of long-term commitB 4

Issue 12/2018 | ModernEquineVet.com

ment involved with these horses as well. You’re looking at years—not months. People have to understand the importance of the commitment.” Dr. Bidwell, who is co-owner of East-West Equine Sports Medicine in Lexington, Ky., discussed several traditional and nontraditional analgesic techniques in a session sponsored by Boehringer Ingelheim.

“You cannot beat continuous icing. It’s recommended up to 48 hours at least.” She typically places the feet in feed tubs and fills them with ice water. “When you have a horse that develops laminitis, you have to make sure everyone involved understands that there is going to be a lot of work involved,” she said. The horse’s shoes should be removed, the feet should be protected with pads, and the footing

First things first

“For acute laminitis, icing is still number one,” Dr. Bidwell explained.

Shutterstock/Erik Kunddahl

Treating Laminitis Pain in Ambulatory Practice

Startwith it. Staywith it.

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For thirty years, Dr. Marvin Beeman, a founder of Littleton Equine Medical Center, has counted on Adequan® i.m. (polysulfated glycosaminoglycan) for his patients. He even uses it on his own horse, Foxy, his beloved third-generation homebred mare. Adequan® has helped keep Foxy perfoming into her teens—so together, they’re still galloping strong. Only Adequan® may help improve joint function by: 1, 2 REVERSING the disease cycle REPAIRING cartilage RESTORING joint lubrication and REDUCING inflammation to help keep joints moving and horses performing.

Thirty years of love and Adequan i.m. says it all.

When you and your veterinarian start with Adequan® i.m. and stay with it, your horse may enjoy greater mobility over a lifetime.3, 4

Ask your veterinarian if Adequan® is the right choice for your horse. Visit adequan.com. 1 Adequan® i.m. [package insert]. Shirley, NY: Luitpold Animal Health; 2008; 2017. 2 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model. J Equine Vet Sci 1993; 13: 696-703. 3 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse. St. Louis, MO: Elsevier, 2016; 33-48. 4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57.

INDICATIONS Adequan® i.m. (polysulfated glycosaminoglycan) is recommended for the intramuscular treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal and hock joints in horses. IMPORTANT SAFETY INFORMATION There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. Studies have not been conducted to establish safety in breeding horses. WARNING: Do not use in horses intended for human consumption. Not for use in humans. Keep this and all medications out of the reach of children. CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. Proud Sponsor Please see Full Prescribing Information at www.adequan.com. Adequan® and the Horse Head design are registered trademarks of Luitpold Pharmaceuticals, Inc. © Luitpold Animal Health, division of Luitpold Pharmaceuticals, Inc. 2018. PP-AI-US-0132 7/2018

LAMINITIS

Biologically Useless Pain TYPES OF PAIN Acute pain is a physiologic pain that serves a protective function and prevents people (or animals) from doing something harmful, such as holding their hands over a fire for too long. If that pain is not dealt with, it becomes chronic—or pathologic—pain. “It has no biological function,” said Lori A Bidwell, DVM, DACVAA, co-owner of East-West Equine Sports Medicine in Lexington, Ky. Chronic pain is associated with elevated circulating stress-associated hormones, altered homeostasis, and altered gene expression. Neuropathic pain is chronic pain resulting from an injury involving the peripheral or central nervous systems. This pain serves no protective function. It is essentially a malfunction of the CNS, in which the nerve has become the source of the pain. “Veterinarians have all seen a horse with chronic laminitis that just wasn’t the same horse as it was the previous year,” she explained. “The hair coat is different, the facial expressions are different, and their whole body has changed. That’s due to the alteration in gene expression and the chronic circulating stress hormones.”

in the stall should be changed to sand or deep shavings, but icing is still on top of the list.

NSAIDs Are Golden

Photo courtesy of Ben Greathouse

Nonsteroidal anti-inflammatory drugs (NSAIDs), phenylbutazone or flunixin meglumine, are still the gold standard of pain management for laminitic horses. “Phenylbutazone is my drug of choice,” Dr. Bidwell said. “I give 2 g once daily for adult horses. I always add omeprazole [for protection f the stomach] at a quarter-tube daily. You don’t need a

Issue 12/2018 | ModernEquineVet.com

full tube for prevention, but the horses do not feel well, so they’re not going to eat like they normally do. You have to do something to protect the stomach.” For horses that do not tolerate NSAIDs, Traumeel is a homeopathic analgesic that Dr. Bidwell has found to be useful. The FDA has not approved this drug. Ingredients include arnica, calendula, chamomile, daisy and deadly nightshade. The drug is legal for FEI competition, but the USEF has banned the drug due to the inclusion of the nightshade. “These horses probably aren’t

going to be competing while they have laminitis, but it’s still a good thing to know,” Dr. Bidwell said.

Other analgesics

Following NSAIDs in the treatment of the acute phase of laminitis, Dr. Bidwell adds more anti-inflammatories. For detomidine, she uses 0.01 or 0.02 mg/kg IM—about 5 to 10 mg for a 1,000-lb horse. “I combine that with butorphanol at 0.05 to 0.1 mg/kg SC,” she said. “We now know that SC butorphanol lasts for up to 5 hours, so this is a useful treatment. Most people don’t carry morphine in their truck, but most people have butorphanol.” Lidocaine patches are also a handy addition. Unlike fentanyl patches, the lidocaine is infused as a gel. This means it’s possible to cut the patches to size. The patches work locally, rather than systemically. “For fentanyl patches, you have to place them over major blood vessels, so you get systemic effects,” she explained. “Lidocaine patches truly just work at the A-delta fibers.” Dr. Bidwell places small patches over the cannon bone and around the pastern. Visible pain relief is seen commonly within 30 minutes, and it wanes at about 11 hours. “We have used patches on a laminitic horse for 2 weeks straight,” she said. “We changed the patches every 12 hours, but never detected lidocaine in the bloodstream, but it is detectable in the urine.”

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LAMINITIS

Evaluation Time PAIN SCALES Veterinarians must be thoroughly involved with laminitic horses during the first week of care. Patient comfort should be evaluated daily, and a pain scale should be developed, Lori A Bidwell, DVM, DACVAA, co-owner of East-West Equine Sports Medicine in Lexington, Ky. “There are great pain scales out there, but most people don't utilize them,”she said. “Every time you look at a horse, look at their attitude, appearance, appetite, mobility, heart rate and gastrointestinal motility. Make a scale. You can make it 0 to 10 or 0 to 100, but just make a scale.” She also recommended including pictures of the horse in the record in cases where the owner is not present for treatments. Some owners may not see what is happening with their horse, and a visual record of the horse’s progression may help owners make appropriate decisions. “Also, alter your analgesic protocol based on your findings,” she said. “Look at the horse every day, and then make changes to your plan.”

Local anesthesia is not always recommended in horses with laminitis, since having a horse moving around in the initial phase is not desirable. Instead, Dr. Bidwell uses “veggie blocks” or sarapin as an abaxial nerve block. “Sarapin has anti-inflammatory and analgesic effects,” she added. “It’s used for neuropathic pain in humans.”

Long-term Care

While NSAIDs are the standard of care, methadone, tramadol and gabapentin may be helpful in the long-term. Methadone is prohibitively expensive as an injectable, but oral tables can be more affordable. It is a mu-receptor agonist, but it does have some NMDA receptor activity. It is 3 times as effective as morphine. “It is an option for that pregnant mare with laminitis that you

are just trying to keep comfortable until foaling.” Dr. Bidwell has not had much success with tramadol, but she has heard favorable stories from her colleagues. She likes to think of it as another option for that one case where not much is working. Gabapentin is useful for quieting excitable nerves to allow other drugs to work. It has been used to great effect in some horses, but many show no effect. Dr. Bidwell also emphasized that a horse’s anxiety should not be overlooked when treating chronic pain. “These horses are standing on the source of the pain,” she said. “There’s a lot of anxiety associated with having to walk like that.” Midazolam, detomidine and acepromazine, as well as herbal supplements and acupuncture, are good options for the pain-related anxiety, she added. MeV

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INFECTIOUS DISEASES

GRAM-NEGATIVES PROVE LETHAL IN EQUINE JOINT INFECTIONS B

New research shows that horses infected with sep-

tic joints linked to gram-negative bacteria, such as Enterobacteriaceae, are significantly more likely to die of the infection than are animals with other forms of microbes. The retrospective study found that gram-negative infections are less common—but significantly more deadly—than gram-positive infections, particularly when they exhibit resistance to current antimicrobial agents. 10

Issue 12/2018 | ModernEquineVet.com

But they also appear to be associated with telltale inflammatory indicators in affected joints—markers that could give equine veterinarians clues about refining therapy. Synovial infections are a significant source of morbidity and mortality for horses. An estimated 6–10% of affected animals will require euthanasia even after aggressive treatment. Even those that survive frequently suffer prolonged problems with their joints. “Septic synovial structures are true emergencies and should be referred if the logistics do not allow you to conduct aggressive and sustained therapy,” said Thomas P. Schaer, VMD, the director of the Preclinical Service Core and Orthopedic Surgery, Section of Surgery, at the University of Pennsylvania, School of Veterinary Medicine New Bolton Center, and a co-author of the study. “A favorable outcome is severely impaired if a patient does not get properly treated from the beginning. Appropriate choice and sustained antimicrobial chemotherapy are important components of a multipronged approach to treatment.” For the study, researchers at PennVet’s New Bolton Center in Kennett Square, Pa., looked at the medical records of 206 horses treated at PennVet for septic synovitis between 2010 and 2015. Affected joints by order of frequency included the tarsocrural joint (23.3%),

Photo courtesy of Dr. Thomas Schaer

Three different pathogenic bacteria photographed using different imaging techniques. First column depicts macroscopic images of bacterial aggregates in synovial fluid of horses. The middle column shows the same bacterial cluster using confocal microscopy, which allows the study of various material components making up the cluster. The third column shows scanning electron microscopy of the same bacterial cluster allowing the study of 3 dimensional arrangement of clusters including the bacteria proper (arrows).

by Merial

in a p A O g in g a n a m e s u a c Be in. shouldn’t cause more pa

ty profile.

ceptional safe ex an ith w y ac fic ef s er liv EQUIOXX de

tis pain and oice for treating osteoarthri ch ht rig the is XX UIO EQ d you’ll fin When you do the research, . inflammation for your clients for horses – spares COX-1

NSAID XX – the first and only coxib • First and Only – EQUIO 1 , including while inhibiting COX-2 * ective than phenylbutazone eff 2 re mo or ive ect eff as ed provement scores UIOXX was rat im l EQ ral dy, ove stu a and In e – enc cy fer ca um Effi • , joint circ nipulation, range of motion ;3,4 improvement in pain on ma studies than any other NSAID ety saf in ses hor re mo on n tested • Safety – EQUIOXX has bee ects most horses had no side eff e, dos ed at the recommend o aid in compliance up to 24 hours which can als n pai ls tro con e dos e On – • Convenient been determined. *Clinical relevance has not

D out to pasture. See how Time to put your old NSAI rence for your clients. ffe di a e ak m n ca X OX UI EQ

EQUIOXX.com

Available in three formulations to fit in and out of competition needs: Injection, Paste and Tablet. IMPORTANT SAFETY INFORMATION: As with any prescription medication, prior to use, a veterinarian should perform a physical examination and review the horse’s medical history. A veterinarian should advise horse owners to observe for signs of potential drug toxicity. As a class, nonsteroidal anti-inflammatory drugs may be associated with gastrointestinal, hepatic and renal toxicity. Use with other NSAIDs, corticosteroids or nephrotoxic medication should be avoided. EQUIOXX has not been tested in horses less than 1 year of age or in breeding horses, or pregnant or lactating mares. For additional information, please refer to the prescribing information or visit www.equioxx.com. Merial is now part of Boehringer Ingelheim. ®EQUIOXX is a registered trademark of Merial. ©2018 Merial, Inc., Duluth, GA. All rights reserved. EQU-0460-JH0218

Data on file at Merial, Safety Study, PR&D 0144901. Doucet MY, Bertone AL, et al. Comparison of efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis. J Am Vet Med Assoc. 2008;232(1):91-97. 3 EQUIOXX product labels and FOI summaries and supplements. 4 Data on file at Merial, Clinical Experience Report PHN 471, PR&D 0030701. 1 2

INFECTIOUS DISEASES

CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. EQUIOXX® (firocoxib) is indicated for the control of pain and inflammation associated with osteoarthritis in horses. Firocoxib belongs to the coxib class of non-narcotic, nonsteroidal anti-inflammatory drugs (NSAID). CONTRAINDICATIONS: Horses with hypersensitivity to firocoxib should not receive EQUIOXX.

Horses should undergo a thorough history and physical examination before initiation of NSAID therapy. Appropriate laboratory tests should be conducted to establish hematological and serum biochemical baseline data before and periodically during administration of any NSAID. NSAIDs may inhibit the prostaglandins that maintain normal homeostatic function. Such anti-prostaglandin effects may result in clinically significant disease in patients with underlying or pre-existing disease that has not been previously diagnosed. Treatment with EQUIOXX should be terminated if signs such as inappetance, colic, abnormal feces, or lethargy are observed. As a class, cyclooxygenase inhibitory NSAIDs may be associated with gastrointestinal, renal, and hepatic toxicity. Sensitivity to drug-associated adverse events varies with the individual patient. Horses that have experienced adverse reactions from one NSAID may experience adverse reactions from another NSAID. Patients at greatest risk for adverse events are those that are dehydrated, on diuretic therapy, or those with existing renal, cardiovascular, and/ or hepatic dysfunction. The majority of patients with drug-related adverse reactions recover when the signs are recognized, drug administration is stopped, and veterinary care is initiated. Concurrent administration of potentially nephrotoxic drugs should be carefully approached or avoided. Since many NSAIDs possess the potential to produce gastrointestinal ulcerations and/or gastrointestinal perforation, concomitant use of EQUIOXX with other anti-inflammatory drugs, such as NSAIDs or corticosteroids, should be avoided. The concomitant use of protein bound drugs with EQUIOXX has not been studied in horses. The influence of concomitant drugs that may inhibit the metabolism of EQUIOXX has not been evaluated. Drug compatibility should be monitored in patients requiring adjunctive therapy. The safe use of EQUIOXX in horses less than one year of age, horses used for breeding, or in pregnant or lactating mares has not been evaluated. Consider appropriate washout times when switching from one NSAID to another NSAID or corticosteroid. The Safety Data Sheet (SDS) contains more detailed occupational safety information. For technical assistance, to request an SDS, or to report suspected adverse events call 1-877-217-3543. For additional information about adverse event reporting for animal drugs, contact FDA at 1-888-FDA-VETS, or http://www.fda.gov/AnimalVeterinary. Rev 10/2016

Photo courtesy of Dr. Thomas Schaer

WARNINGS: EQUIOXX is for use in horses only. Do not use in horses intended for human consumption. Do not use in humans. Store EQUIOXX Tablets out of the reach of dogs, children, and other pets in a secured location in order to prevent accidental ingestion or overdose. Consult a physician in case of accidental human exposure.

A joint tap to obtain a specimen for testing.

metacarpo(tarso)phalangeal joint (16.5%) and the digital flexor tendon sheath (13.1%). Approximately 86% of the animals survived their infections and were discharged from the hospital; the rest required euthanasia. Samples of synovial fluid found that 48% were culture negative for bacteria, while 52% had isolatable strains of microbes. Animals that tested negative tended to have better outcomes, including greater odds of discharge, less time in the hospital and a less expensive course of care. Of those, roughly two-thirds were gram-positive—mostly Staphylococcaceae and Streptococcaceae—and about 28% were gram-negative.

Most common problem

Enterobacteriaceae including Escherichia coli, Pseudomonas aeruginosa and Actinobacillus were the most frequent gram-negative bacteria, accounting for 17% of such infections. The presence of gram-negative organisms was associated with dramatically increased odds of euthanasia compared with gram-positive microbes. For example, horses with coagulase-positive staph had nearly an eightfold increased risk of euthanasia; for enterococci, the risk was more than 18 times greater; and for Enterobacteriaceae, the risk 12

Issue 12/2018 | ModernEquineVet.com

was more than 31 times higher. The overall odds ratio for euthanasia associated with gram-negative germs was roughly 5, according to the researchers. Horses with multidrug resistant (MDR) microbes fared particularly poorly. The odds ratio for animals with MDR grampositive strains was 1.85, but soared to 119 if the MDR organisms were gram-negative, the researchers found. “An injury with a suspicion of synovial structure involvement is an emergency and must be treated as such—aggressively or referral,” Dr. Schaer told Modern Equine Vet. “Obtaining a culture with antibiogram and susceptibility pattern and clinical pathology of synovial fluid is helpful but initiating a multimodal treatment regime should not be delayed until these results are in. This can be accomplished by systemic and regional antimicrobial therapy, anti-inflammatory administration, synovial structure lavage, and primary/secondary wound care.” The researchers did identify indicators of gram-negative infections, which included a significantly higher number of total nucleated cells in the synovial fluid, a greater percentage of neutrophils and a smaller proportion of lymphocytes, and a higher level of systemic fibrinogen.

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INFECTIOUS DISEASES

As for culture-negative patients— these present “a tough challenge to all clinicians regardless of their patient [humans or animals]. It may oftentimes be associated with biofilm infections, which are notoriously hard to diagnose and treat,” he explained. “It is not that uncommon that the offending pathogen is never identi-

fied and in some cases the patients may respond favorably to the initiated therapy without ever identifying the offending pathogen. It is therefore critical that any initial therapy is started immediately. Judicious selection of broad-spectrum antimicrobials requires knowledge of the most common organisms responsible

for these types of infections. This is where experience and good client communication is paramount for success. If referral is an option for a horse owner, it should be considered immediately to give the horse the best prognosis for return to function, not days later after treatment has failed.” MeV

For more information: Gilberti JM, Schnabel LV, Stefanovski, et al. Gram-negative multi-drug resistant bacteria influence survival to discharge for horses with septic synovial structures: 206 cases (2010–2015). Vet Microbiol. 2018;226:64-73. Dr. Schaer and his colleagues are conducting additional studies with other groups looking at biofilm infections, septic joints and host-microbe interactions. For more information, visit https://www.vet.upenn.edu/people/faculty-clinician-search/THOMASSCHAER

Magnesium May Not Be a Calming Influence After All

Magnesium might not make a difference in calming horses.

Issue 12/2018 | ModernEquineVet.com

Photo courtesy of SPILLERS

The latest research suggests that magnesium does not significantly calm horses. When a horse's flight reaction is felt to be excessive, some owners opt to use calming supplements, usually containing magnesium. A previous study of a small number of Standardbreds, published in 2015, showed that magnesium aspartate (a very available source of magnesium) could significantly reduce their average reaction speed response. However, there was a question about whether this would be seen in other animals and even whether the aspartate might have been responsible for this effect because of its action as an amino acid neurotransmitter. Glenys Noble, PhD, of the Charles Sturt Universi-

ty in New South Wales, Australia, and the WALTHAM Equine Studies Group aimed to determine whether the magnesium or the aspartate was responsible for the 2015 study results and whether these original findings were repeatable. Eighteen animals (6 ponies, 6 Arabians and 6 Thoroughbreds) were randomly fed 3 different diets over 7 days. The diets comprised a control hay-based diet providing the National Research Council’s recommendations for magnesium, this control diet plus the same amount of supplementary magnesium (10 g/500 kg horse) or aspartate, as was fed in the original paper (provided as magnesium aspartate or sodium aspartate respectively). Some animals decreased their reaction speed and others increased it when fed the magnesium aspartate or the sodium aspartate, compared with showing no significant effects when fed the control diet (unpublished data). At no time did the horses demonstrate any characteristics of being either sedated or more excited when being fed the diets. This indicates that neither the magnesium nor the aspartate had a consistent effect, the researchers said. “As it stands, these results suggest that magnesium supplementation cannot be relied on to modify horses’ reaction speeds. It may be wiser to focus on training and habituation to stressful situations to help manage reactive behavior, rather than to rely solely on magnesium-based products,” said Clare Barfoot, RNutr, the research and development manager at SPILLERS, a nutrition company. MeV

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ANESTHESIOLOGY

Horses of a

Different Color Anesthesia Needs of Mules, Miniatures and Hybrids

When presented with a miniature horse, mule, or hy-

brid equine in need of anesthesia, some practitioners may be tempted to treat the animal as they would treat a fullsized horse, just with a smaller dose. Nora Matthews, DVM, DAC-VAA, a clinical anesthesiologist and past president of the American College of Veterinary Anesthesia and Analgesia, broke down some key differences between “standard” horses and the “alternative equines.” For an equine patient outside the norm, Dr. Matthews recommended that practitioners ask themselves what is different about the patient, and how these differences will affect treatment.

B 16

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Shutterstock/Mr.ES

Miniature Horses

The obvious difference in miniature horses is that they are miniature, and miniature foals are even “more miniature,” she reminded. “We tend to forget this as equine practitioners,” Dr. Matthews said. “We get into the habit of using 20- or 35-mL syringes and 18-gauge needles. Our selection of ‘small’ may not be very good.” Drug dosages must also be downsized. For a 100-kg mini horse, the average preanesthetic dose of xylazine is approximately 1 mL—much less than many practitioners are used to. For maintenance of injectable anesthesia, a triple drip (guafenesin-ketamin-xylazine [GKX]) drip rate should be carefully quantitated instead of running it as an open-flow from a 1-L bag. The low drip rate for miniature horses can be difficult to control without careful observation. Transferring the drugs to a smaller container could prevent an overdose in tiny patients.

NEWS NOTES

Smaller anesthesia circuits and endotracheal tubes will also be needed. “These patients are going to have small animal complications, such as hypothermia and the potential for fluid volume overload,” she said. If miniature horses keep finding their way into your practice, Dr. Matthews recommended maintaining a relationship with a nearby small- or mixed-animal practitioner with smaller anesthesia machines and technicians who are more comfortable handling smaller animals. “Your big equine anesthesia machine isn’t going to work on a miniature horse or foal because the circuit is too big, and there is too much resistance,” she explained. “Occasionally, I would walk a miniature horse over to a small animal clinic and anesthetize it there. It didn’t make me very popular [at the clinic], but it was a reasonable thing to do.” Recovery from anesthesia is typically easier in miniature horses when compared with their full-size counterparts. “You can usually just wrap them up and hang on to them,” Dr. Matthews said. “If it’s an adult, sometimes you can just pick them up and set them on their feet. You don’t have to fight with them too much.”

nists like xylazine or detomidine faster than horses, so they do require bigger doses,” Dr. Matthews said. For example, a mule will typically require about 50% more xylazine than a horse. Induction with ketamine will be effective, but a standard dose of 2.2 mg/kg will likely only last 8 to 10 minutes. “For most procedures, you don’t have as much surgical time as you would in a horse,” she explained. “Be prepared to redose or supplement with GKX. I typically double the ketamine dose in my GKX cocktail. Instead of 1 mg/ kg ketamine, I make it 2 mg/kg. Maintain with that infusion for the duration needed.” For recovery, mules are all over the board. They can be calm, or not. Dr. Matthews recommends that obtaining details about the mule’s training, activities and work history from the owner could be helpful.

Mules, miniatures and hybrids are not just "small" horses when it comes to anesthesia.

Mules

Little is known about mules in terms of normal values and pharmacokinetic differences, which can make administration of anesthesia and subsequent monitoring difficult. “We know they metabolize ketamine faster than horses, and we know they metabolize alpha-2 ago-

Zebras and Hybrids

Not much is known clinically about zebras and hybrids such as Zorses, Z-donks, and other Zebroids, but Dr. Matthews treats them like donkeys or mules. “I expect them to be different from the horse, even though I’m not exactly sure what to expect,” she said. One important note when handling a zebra is that they are remarkably good at biting, and they will hang on. “Whether they are good to work with depends on how much handling they have had,” she explained. “Many of them have been well handled, but the owner is likely going to be a huge asset in telling you what has and has not been done with the animal.” MeV

Luitpold Animal Health Becomes American Regent Animal Health On Jan. 1, Luitpold Animal Health becomes American Regent Animal Health. The name change reflects the company's commitment to animal health while unifying its operations under a common set of values, goals and operating principles, according to a statement from the company. Luitpold Pharmaceuticals Inc. will streamline its operations by absorbing its wholly owned subsidiaries, American Regent Inc. and PharmaForce Inc., into 1 corporate entity as of Dec. 31, 2018. Although Luitpold will be the surviving entity, its name will be changed to “American Regent Inc.” following the merger. “This change allows us to draw on the strength of the American Regent brand and U.S. manufacturing footprint to continue delivering on the promise of better solutions for the health and well-being of animals,” explained Joel Steckler, vice president, Commercial Operations, American Regent Animal Health.

“Our commitment remains unwavering, as this evolution will position us to stay relevant to the needs of our customers and continue advancing a leading portfolio of animal health products that is anchored by Adequan,” he said. American Regent is a well-recognized brand with 50 years of history that is best known for its human pharmaceutical products. The company is known widely in the United States for providing high-quality, trusted products for treating iron deficiency and generic specialty injectables. “While our company name is changing, all customer service, manufacturing, sales and distribution channels will remain the same,” Mr. Steckler added. “We will continue to provide our customers with proven products and continue to place emphasis on best-of-class service.” Luitpold Pharmaceuticals entered the animal health market in 1984. The company released its marquis animal health product, Adequan i.m. for horses in 1989 and Adequan for dogs in 1997. The company maintains the only FDA-approved polysulfated glycosaminoglycan manufacturing site in MeV the world. ModernEquineVet.com | Issue 12/2018

NEWS NOTES

The thyrotropin-releasing hormone (TRH) stimulation test is recommended as a dynamic test for the diagnosis of pituitary pars intermedia dysfunction (PPID) in donkeys. This prospective study by S. Mejia-Pereira and colleagues in Spain and the United States aimed to evaluate dynamic testing for PPID in donkeys. Six donkeys with clinical signs consistent with PPID and a basal adrenocorticotropic hormone (ACTH) concentration >50 pg/mL were included in the study. A dexamethasone suppression test (DST), thyrotropin-releasing hormone (TRH) stimulation test and combined DST-TRH challenge were performed in all animals during the summer months with a 1-week washout period between tests. The TRH stimulation test identified all 6 donkeys as

having PPID, whereas the DST and the DST-TRH only identified 3 and 4 donkeys, respectively. In addition, the agreement between the DST and the DST-TRH tests was poor, according to the researchers. MeV

For more information: Mejia-Pereira S, Perez-Ecija A, Buchanan BR, et al. Evaluation of dynamic testing for pituitary pars intermedia dysfunction diagnosis in donkeys. Equine Vet J. 2018 Oct. 26 (Epub ahead of print). https://onlinelibrary.wiley.com/doi/pdf/10.1111/evj.13034

Merck Animal Health/AAEP Foundation Scholarship Awarded to 5 Promising Equine Veterinary Students The Merck Animal Health/American Association of Equine Practitioners (AAEP) Foundation scholarship recognized 5 promising veterinary students committed to a career in equine medicine a $5,000 scholarship: •A bigail Illingsworth, Tufts University, class of 2020 • Persia Neumann, University of CaliforniaDavis, class of 2019 • Kate Rigby, Kansas State University, class of 2019 • Catherine Thurston, University of Pennsylvania, class of 2019 • Zoe Williams, Michigan State University, class of 2020 To be eligible, applicants must be second- or thirdyear veterinary students dedicated to equine medicine and active within any of the AAEP’s 39 student chapters at colleges of veterinary medicine in the U.S., Canada, Europe and the Caribbean. The scholarships are awarded to students for their academic excellence 18

Issue 12/2018 | ModernEquineVet.com

and leadership. MeV For more information, visit www.aaepfoundation.org.

BI Announces Winners of 2018 Champions of the Cause Awards Boehringer Ingelheim awarded the 2018 Champions of the Cause Award to Lisa Amtower from Rhinebeck Equine Hospital in Rhinebeck, N.Y., and Ashley Cashwell from Bristol Veterinary Service in Salem, Wisc. Presented in partnership with EquiManagement and the American Association of Equine Veterinary Technicians (AAEVT), the award was given for their passion for equine health, commitment to understanding equine well-being and dedication to improving the equine health industry. Learn more about the award, http://www.championsofthecause.com.

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TRH Stimulation Test Best for PPID in Donkeys

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