The Modern Equine Vet September 2017

The Modern

Equine Vet www.modernequinevet.com

Giving Life to Old Horses

A Win for Everyone Tackling Coronavirus Should Equine Lameness Be Redefined?

Be Still My Heart Technician Update: Iron Will

Vol 7 Issue 9 2017

TABLE OF CONTENTS

GERATRICS

A Win-Win-Win for All Parties

4 Giving New Life to Old Horses Cover photo: iStock/kruwt

ORTHOPEDICS

Should Equine Lameness Be Redefined? ...........................................................................11 CARDIOLOGY

New Treatment Calms Fluttering Hearts............................................................................12 TECHNICIAN UPDATE

Iron Will...........................................................................................................16 NEWS

UC Davis Equine Researchers Tackling Coronavirus ...................... 3 Storms May Cause Surge of Seasonal Pasture Myopath ..........14 Making Sure Patients Are Safe on the Road...................................15 Horses Masticate Similarly to Ruminants........................................19 ADVERTISERS Equinosis........................................................................ 3 Boehringer Ingelheim................................................ 5

Merck Animal Health.................................................. 7 AAEVT............................................................................21

The Modern

Equine Vet SALES: Matthew Todd • ModernEquineVet@gmail.com EDITOR: Marie Rosenthal • mrosenthal@percybo.com ART DIRECTOR: Jennifer Barlow • jbarlow@percybo.com CONTRIBUTING WRITERS: Paul Basillo • Kathleen Ogle COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers PERCYBO media  publishing

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Issue 9/2017 | ModernEquineVet.com

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NEWS NOTES

The origin of equine coronavirus (ECoV) still remains a mystery, although some suspect it may have developed from bovine coronavirus and spread across species.

Among horses, ECoV is mostly spread via the fecal-oral route, not through respiratory secretions, according to Nicola Pusterla, Dr Med Vet, professor of Medicine and Epidemiology at the University of California Davis. Initially, ECoV was only associated with foals, but there have been reports among adults.

Most horses with ECoV will present as anorexic (98%) and lethargic (88%), with an elevated rectal temperature (≼ 101.5°F; 81%). Less common signs may include diarrhea, colic and neurologic deficits, such as aimless wondering, headpressing, recumbency or seizures. However, veterinarians should not assume that symptomatic horses have ECoV and asymptomatic horses do not, he said. PCR testing confirmed that 10% to 20% of asymptomatic horses involved in outbreaks have detectable ECoV in their feces.

The infection is generally short-lived. Clinical signs only persist for one to four days and are cleared with

Photo courtesy of UC Davis

UC Davis Equine Researchers Tackling Coronavirus

general supportive care. And the mortality rate is low, he said. In a recent UC Davis study, only 8% of horses infected with ECoV died as a result of complications such as endotoxemia, sepsis or hyperammonemic encephalopathy. Dr. Pusterla recommended that veterinarians encourage horse facilities to continuously enforce biosecurity protocols to stop the spread of ECoV and take extra precautions at events where there are large groups of horses.

MeV

www.equinosis.com

GERIATRICS

A Win-Win-Win for All Parties

Shutterstock/AlinaMD

Giving New Life to Old Horses Clients want more veterinary services for their geriatric horses, so a relatively new area of growth promises to be a win-win-win for all parties: aging horses, clients and clinics.

The role of the old horse is changing—it’s no longer your clients’ old companion horses in the backyard or a horse that is put out to pasture, emphasized Dianne McFarlane, DVM, PhD, DACVIM, professor in the department of physiological sciences, Center for Veterinary Health Services at Oklahoma State University, Stillwater.

To create and grow a healthy geriatric program at the practice level B 4

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matter of prolonging their competitive life span, but of keeping them active so they remain useful and productive family members as long as their health and soundness allows.”

Horses are living well into their 30s, some even into their 40s. “Our job is to maximize their quality of life until doing so is no longer a viable option,” she said, adding that practitioners can choose which approach to a geriatric medicine service best fits their practice needs.

• Full package: Clients pay a single up-front price that includes a complete geriatric examination as well as relevant diagnostic testing (eg, serum chemistry panels to screen for occult disease, fecal egg counts, endocrine testing). Dental exams and intervention, nutritional consults, fitness programs, early

takes finely tuned client–veterinarian teamwork and creative clinic marketing, Dr. McFarlane added.

Practitioners should think of the aging equine patient as performance horses—not just pasture ornaments—because nearly half of horses older than 20 years of age are still actively performing, according to Dr. McFarlane. “These horses represent the greatest investment in training and time that we have, and ensuring that they remain in performance [events] longer is an economical as well as emotional plus.”

"But," Dr. McFarlane said, “they also are well-loved members of each client’s family circle, so it isn’t just a

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MARQUIS® (15% w/w ponazuril) Antiprotozoal Oral Paste

Some diagnoses

you have to face head-on.

Equine Protozoal Myeloencephalitis (EPM) is an expert in deception and your clients may at first confuse it with other issues, such as lameness. Only stopping the parasite responsible can stop EPM from causing further damage to the horse’s brain and CNS. Time matters. The sooner EPM is detected and diagnosed, the better the chance for recovery.

That’s why you need a tube of MARQUIS on every truck to initiate treatment immediately. MARQUIS is a powerful anti-protozoal.

Only MARQUIS offers a 3X loading dose protocol that allows it to reach steady state in 24 to 48 hours.*,1 *Clinical relevance has not been determined.

The signs can be subtle.

The treatment should be aggressive.

Clients can save on their next purchase.

MAX.merial.com MARQUIS Freedom of Information Summary and Supplement and product label.

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IMPORTANT SAFETY INFORMATION: The safe use of MARQUIS in horses used for breeding purposes, during pregnancy, or in lactating mares, has not been evaluated. In animal safety studies, loose feces, sporadic inappetence, lost weight, and moderate edema in the uterine epithelium were observed.

Merial is now part of Boehringer Ingelheim. ‰MARQUIS is a registered trademark, and ™MAX, Merial Awards Xpress is a trademark, of Merial. ©2017 Merial, Inc., Duluth, GA. All rights reserved. EQUIOMQ1506-B (04/16)

GERIATRICS

MARQUIS

®

(15% w/w ponazuril) Antiprotozoal Oral Paste

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

For The Treatment Of Equine Protozoal Myeloencephalitis (EPM) In Horses For Oral Use Only

A geriatric program's success centers around client participation: Getting owners to monitor horses regularly and track health markers.

BRIEF SUMMARY Before using MARQUIS, please consult the product insert, a summary of which follows:

disease intervention, as well as educational events and social activities may be covered, with additional services available at a discount.

• Partial package: Partial packages may include a subset of the services covered by the full package, such as twiceyearly examinations and fecal egg counts. As with the full package, additional services may be discounted.

• Geriatric examination (at minimum): A detailed geriatric examination can be added as a unique and comprehensive standalone service, with all other costs being piecemeal.

This examination should be approached like a prepurchase exam, that is, scheduling more time for the visit and critically examining each body system.

INDICATIONS MARQUIS (ponazuril) is indicated for the treatment of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona.

WARNINGS For use in animals only. Not for use in horses intended for food. Not for human use. Keep out of reach of children.

PRECAUTIONS Prior to treatment, a complete neurologic exam should be completed by a veterinarian. In most instances, ataxia due to EPM is asymmetrical and affects the hind limbs. Clinicians should recognize that clearance of the parasite by ponazuril may not completely resolve the clinical signs attributed to the natural progression of the disease.

The prognosis for animals treated for EPM may be dependent upon the severity of disease and the duration of the infection prior to treatment. The safe use of MARQUIS (ponazuril) in horses used for breeding purposes, during pregnancy, or in lactating mares, has not been evaluated. The safety of MARQUIS (ponazuril) with concomitant therapies in horses has not been evaluated.

ADVERSE REACTIONS In the field study, eight animals were noted to have unusual daily observations. Two horses exhibited blisters on the nose and mouth, three animals showed skin reactions for up to 18 days, one animal had loose stools, one had a mild colic on one day and one animal had a seizure while on medication. The association of these reactions to treatment was not established.

ANIMAL SAFETY SUMMARY MARQUIS (ponazuril) was administered to 24 adult horses (12 males and 12 females) in a target animal safety study. Three groups of 8 horses each received 0, 10 or 30 mg/kg (water as control, 2X and 6X for a 5 mg/kg [2.27 mg/lb] dose). Horses were dosed after feeding. One half of each group was treated for 28 days and the other half for 56 days followed by necropsy upon termination of treatment. There were several instances of loose feces in all animals in the study irrespective of treatment, sporadic inappetence and one horse at 10 mg/kg (2X) lost weight while on test.

Loose feces were treatment related. Histopathological findings included moderate edema in the uterine epithelium of three of the four females in the 6X group (two treated for 28 days and one for 56 days).

For customer care or to obtain product information, including a Material Safety Data Sheet, call 1-888-6374251 Option 2, then press 1. ®MARQUIS is a registered trademark of Merial. ©2016 Merial, Inc., Duluth, GA. All rights reserved.

Clients: Key to Success

The success of a geriatric program centers around client participation—getting owners to observe and monitor horses regularly and tracking health markers as the horse ages (see Tools for Your Clients).

Key markers include body weight, body condition, hair coat and shedding, hoof growth and quality, time it takes to eat meals, behavior, and spontaneous activity.

“I can’t emphasize enough the need to build a strong bond that promotes the importance of tracking and recording information on a regular basis,” she explained. “Any sudden change in the horse’s willingness to move, willingness to work or willingness to eat needs to be investigated.”

Some normal aging changes are predictable, including: • Loss of weight (many aging horses are overweight initially), loss of muscle mass and tone; • Loss of flexibility in tendons, liga6

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ments and joints (exercise and fitness are key preventatives); • Loss of tooth root length; and • Lameness and creaky joints.

Ideally, get clients involved early by establishing baseline values before their horse is aged.

“We want them to record information and, when appropriate, take digital photographs,” Dr. McFarlane said. Setting up an online spreadsheet or database gives the client and clinic quick access to information as it is being gathered and updated. Some practice management software and websites provide patient portals for clients to access patient information, as well as educational materials.

For clients who still prefer paper information, Dr. McFarlane suggested providing a notebook or folder of prepared sheets designed for recording specific types of information.

A good starting point is weight. “A perfect time for owners to start monitoring weight is when their horse is in its late teens,” Dr. McFarlane said. Teach owners how to use a weight tape and have them monitor the horse’s weight every other month during the late teen years, then more frequently (every month) as the horse gets older and every two weeks when it is very old.

Also teach owners how to score body condition. “You don’t want clients to just look. You want them to observe, touch, then assign a score,” explained Dr. McFarlane. There are six areas to check—fat over the neck, withers, crease of back, tail, head, ribs, (behind the shoulder at the girth).

As horses age, factors contributing to weight loss include dental abnormalities, improper nutrition, chronic pain, muscle atrophy—secondary to pituitary pars intermedia dysfunction (PPID), malabsorption and parasitism.

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UC Davis (Nicola Pusterla) & Merck Animal Health. Infectious Upper Respiratory Surveillance Program. Ongoing Research 2008-present.

Townsend HGG. Onset of protection against live-virus equine influenza challenge following vaccination naive horses with a modified-live vaccine. Unpublished data.

GERIATRICS

If diet or teeth is not the cause, look at the horse’s environment: “Old horses need to have sufficient time to eat without feeling social pressure from young horses looking to steal their meal,” Dr. McFarlane said, adding that sometimes it is as simple as giving older horses more privacy so they can eat their feed in a relaxed setting.

Environment also can be key when dealing with old-age chronic pain and creaky joints. “You want to make sure the older horse has an adequate-sized stall and a soft place to lie down that also lets the horse get up easily,” she said.

Have owners score chronic pain and report immediately if pain seems

to interfere with quality of life.

Customize exercise and fitness programs to fit the individual needs of each horse. “Remind owners that the best way to avoid loss of aerobic function and flexibility is to keep the horse active—keep them working,” Dr. McFarlane said. Emphasize the key elements of a fitness program: • Keep the horse in steady work.

• Warm-up and cool-down are essential.

• Turnout is important.

• Avoid extreme forced exercise.

• Discuss subtle changes in horse’s willingness to move.

With age, all horses encounter some loss in range-of-motion and

What Is Aging?

Aging is characterized by progressive loss of function over time and an inability to adapt to stress or challenge.

We all age chronologically at the same rate, as each year there is one more candle on the cake. However, physiological aging can differ greatly from person to person or horse to horse. We cannot slow down chronological age but we can try to slow down physiological age, so the 20-year-old horse will act more like a 15-year-old horse and not a 30-year-old horse.

One of the key roles of the veterinarian is recognizing the difference between normal aging and disease. Since the older horse has a harder time recovering from disease and injury, early recognition and intervention are essential to maximizing a positive outcome.

PREDICTABLE AGING CHANGES IN HORSES • Mild loss of muscle mass and loss of aerobic ability • Less flexibility of joints • Decrease in GI absorption • Slower eating due to changes in teeth CHANGES SIGNALING POSSIBLE DISEASE • Severe muscle mass atrophy • Loss of immune competency • Behavioral changes • Failure to shed • Long hair coat • Exercise intolerance • Quidding and/or malodorous breath • Foul nasal discharge • Masses or lumps • Profound or rapid weight loss

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most old horses show some degree of lameness, Dr. McFarlane explained.

Discuss with clients the various treatment options for pain control and flexibility—from joint supplementation to acupuncture to chiropractic to physical therapy.

This is important, stressed Dr. McFarlane, as not only is lameness the No. 1 problem identified by owners and practitioners in aged horses, it also is the top reason for loss of use and death in the performance horse. Common causes of lameness include osteoarthritis, laminitis, soft tissue injury and hoof problems.

“Even an old horse that is no longer in work needs timely farrier care,” Dr. McFarlane said, adding that proper foot care can aid in ease of ambulation, especially for the arthritic animal.

Likewise, in aged horses, failure to shed, late shedding, or incomplete shedding is common and often reported by owners. Shedding abnormalities and bacterial skin infections are often secondary to PPID, Dr. McFarlane said.

To help in recognizing early trends of delayed shedding, ask owners to record the dates when a horse is shedding in spring (photo documentation would be perfect), along with when the horse actually has its summer coat.

With dental problems, practitioners will recognize the signs of bad teeth, but owners may not. “Teach owners how to look for the aging signs of dental disease, including quidding, slow eating, malodorous breath, foul nasal discharge, masses or lumps on the jaw, even weight loss—so they can identify changes in dental integrity,” Dr. McFarlane explained.

When you perform dentistry on old horses, be sure to remove loose teeth but do not try to fix 30 years of dental abnormalities—the goal is to just make the horse comfortable.

ON ARRIVAL

AFTER 6.5 MONTHS

This aged (over 20 years of age) Thoroughbred mare came to us without a history, other than abandonment. We performed a complete and comprehensive geriatric examination and addressed a number of medical problems, including severe weight loss, a high fecal egg count and several loose teeth, which were removed. After being fed lots of Purina Equine Senior and having access to pasture and hay — as well as having all identified medical problems addressed — the mare filled out and recovered nicely. ©2016 Dianne McFarlane; not for reproduction without written permission

Now It’s Your Turn …

Armed with information about the horse’s health status, it’s time to visit the farm, said Dr. McFarlane. But first, carefully review all recorded data collected by the client for clues about the individual horse's healthcare needs. Also, she suggested, bring the clinic’s veterinary records with you or have online access to the records once you arrive.

Treat the geriatric examination as a prepurchase exam, documenting the entire procedure with both photos and videos to assess progression over time. Having twice-yearly geriatric exams—one in the spring and one in the fall—strategically enhances the practitioner’s ability to detect and address seasonally relevant events, such as hair coat, fecal egg counts during grazing season, seasonally strategic testing for endocrine problems, seasonal vaccination, weight assessment and diet adjustments.

At minimum, Dr. McFarlane said, the examination should focus on: • Evaluating body weight and condition (compare with both clinic and owner records)

Document the entire geriatric examination with photos and videos so that you can assess progression over time.

• Listening to the heart in a quiet location • Using a rebreathing bag to listen to the lungs • Completing an ophthalmic evaluation inside, where it is dark enough for a fundic exam • Observing the horse at a walk and trot (photographic documentation helpful) • Submitting samples for lab work, including CBC with fibrinogen, serum chemistry profile, serum amyloid A, endocrine testing (ACTH,

baseline, stimulation test), and fecal egg counts • Reviewing the vaccination plan • Monitoring for timely disease intervention In the old horse, Dr. McFarlane emphasized that screening and monitoring for endocrine disease is important. “You would want to perform either an endogenous ACTH test or TRH stimulation test, measuring ACTH release,” she said, adding that if the phenotype suggests the horse may be insulin dysregulated (obesity, crusty neck, easy keeper), monitor for equine metabolic syndrome, preferably with an oral sugar test. Also, do fecal egg counts at appropriate times.

And, because old horses are more susceptible to disease, monitoring the serum amyloid A concentration can be beneficial. “Typically, this marker does not go up just with age, so the finding can be a nice early warning of concurrent disease,” Dr. McFarlane said.

She also recommended reviewing biosecurity procedures with the client. “With loss of immune competency, emphasize the importance

GERIATRICS

of avoiding contact between the senior horse and horses that are going to and from shows.”

In addition, PPID causes immunosuppression. “[This disease] is difficult to diagnose early, so any old horse may be an early case of PPID and thus may not have optimal immune function,” she explained. “If you see bacterial infection in an old horse, particularly sinusitis, dermatophilosis or foot abscesses, test for PPID.” During each visit (whether a biyearly exam or follow-up visit), reassess the horse’s nutritional requirements. “Try to identify areas of concern so you can intervene early and be proactive,” Dr. McFarlane offered. “We can often delay predictable age-related changes, such as weight loss or exercise intolerance, if we act in a timely manner.”

In a thin, aged horse, it is important to promote a safe environment that allows ample access to feed. Feeding processed or complete senior feeds may promote weight gain in these horses. In the obese aged horse, limit caloric intake and reduce water-soluble carbohydrates in the diet. Provide mineral and trace supplementation, especially if hay is being soaked, as nutrient absorption can be impaired with age.

Help clients understand what to expect as their horses age and how to differentiate between disease and normal aging.

Prioritize Goals

Remember to be creative when designing a geriatric program: Anticipate problems. Act early.

“It’s a matter of helping clients understand what to expect as their horses age and how to differentiate between normal aging changes and disease changes,” Dr. MacFarlane explained. “I’m sure you have gone out to see a horse that is very decrepit, is old, has no weight on it, has a long hair coat—and the client thinks that this is normal aging.”

• Make the learning process a positive, inviting experience. Offer educational events (eg, on ex-

ercise and rehabilitation, nutrition, dental care), and feature a Facebook page for owners to announce their horse’s birthday or other special events.

• Sponsor a performance-based event designed specifically for old horses. “My favorite is when horse shows offer performance classes for horses age 20 or older. These are really popular, and owners and spectators love them,” Dr. McFarlane said.

• Encourage clinic staff (and clients) to participate in the creative process.

“Your goals,” she said, “should center around keeping old horses performing at their original job as long as possible. And when that is no longer possible, keep them performing at a lower level, or perhaps at a different job. When that’s no longer possible, try to maximize the quality of life.” But eventually the necessity to perform humane euthanasia at the most appropriate time becomes a reality.

Today, Dr. McFarlane said, old age represents a vital, growing patient base in equine practice. With clever marketing strategies, a lasting client-clinic partnership and dedicated teamwork, practitioners can create a winning program, she predicted.

MeV

For more information: American Horse Publications: Equine industry survey 2009-2010; sponsored by Intervet/Schering-Plough Animal Health and Pfizer Animal Health. Available from: http:www.americanhorsepubs.org/wp-content/uploads/2015/01/2009-2010-equine-survey-summary-statistics.pdf. du Toit N. Rucker BA. The gold standard of dental care: the geriatric horse. Vet Clin North Am Equine Pract 2013;29(2):521-527.

Ireland JL, Clegg PD, McGowan M, et al. A cross-sectional study of geriatric horses in the United Kingdom. Part 1: demographics and management practices. Equine Vet J. 2011;43(1):30-36.

Ireland JL, Clegg PD, McGowan M, et al. Disease prevalence in geriatric horses in the United Kingdom: veterinary clinical assessment of 200 cases. Equine Vet J 2012:44(1):101-106.

McFarlane D. How to establish a healthcare program for the aging horse in equine practice. Proc 62nd Annu AAEP Conf 2016; 62:464-468.

Siciliano PD. Nutrition and feeding of the geriatric horse. Vet Clin North Am Equine Pract 2002;18(3):491-508.

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ORTHOPEDICS

Equine lameness should be redefined to reflect new digital assessment techniques that use preset parameters to detect gait asymmetries, according to Professor René van Weeren, PhD, professor of Equine Musculoskeletal Biology at Utrecht University, Faculty of Veterinary Medicine in The Netherlands.

The traditional method for detecting equine lameness is subjective, using expert visual evaluation of gait to identify the presence or absence of lameness and the degree of asymmetries, he explained. The lame horse is described as having a disorder, defect or loss of function, which would signal the search for a cause and clinical diagnosis. However, being called “lame” has associated welfare implications if the horse is still asked to perform or if it is being sold, he wrote in the Equine Veterinary Journal.

Advanced computer technology is starting to change all this. Optic motion capture or the use of inertial measurement sensors is now enabling the detailed study and quantification of the horse’s gait as an objective assessment against preset thresholds. The paper “Do we have to redefine lameness in the era of quantitative gait analysis?”

by Prof. Van Weeren and collaborators, pointed out that while these digital systems can overcome the temporal and spatial limitations of the human eye, they rely on one or a number of set gait parameters to decide about lameness.

Although gait analysis is becoming an “indispensable” tool, he said, clinicians cannot use them in a vacuum. Thresholds are based on

a limited reference population, and may not account for horses that have an asymmetric gait.

The individual environmental and mental conditions for each horse and its day-to-day gait variations are also not accounted for. On this basis, to use the term “lame” because a horse demonstrates a subtle gait alteration, causing it to fall below the threshold, could be inappropriate—particularly as it may not affect the horse’s welfare in any way, Prof. van Weeren said.

Prof. Celia Marr, editor of the Equine Veterinary Journal said: “An important first step is for researchers and clinicians to start to discriminate clearly between ‘asymmetry’ and ‘lameness’ and not to use these as interchangeable terms when interpreting gait analysis data.

Asymmetry is often, but not always, a hallmark of lameness, but it is not a clinical term, whereas lameness is.”

Prof. Van Weeren continued: “Digital equine gait analysis is sure to become an indispensable additional tool for clinical decision-making. At this early stage we must define the use of terminology in order to avoid confusion and to prevent the formation of wrong perceptions. Using the term ‘lame’ for any horse falling beyond thresholds set for quantitative gait analysis or not showing the ideal motion pattern when assessed clinically is inadvisable.

“We should reserve the use of that term for horses deemed unfit to compete based on a comprehensive assessment of the animal that includes, but does not rely entirely on, the appreciation of the degree of gait asymmetry.”

Photo courtesy of Professor René van Weeren, PhD

Should Equine Lameness Be Redefined?

Veterinarians must use their clini­-cal acumen to assess that animal. In other words, treat the horse, not the test.

“We obviously agree on the practical aspect of using sensitive objective measures of movement to assess horses," said Kevin G. Keegan, DVM, MS, DACVS, founder and shareholder of Equinosis, which makes inertial measurement sensors (the lameness locator).

“What we do not agree on is what to do about the public perception.

Dr. Marr is suggesting that we need to discriminate between asymmetry and lameness and by definition they are the same thing. Lameness is a clinical sign of asymmetric movement," Dr. Keegan told The Modern Equine Vet. “She is suggesting that these terms be differentiated.

“I do not think they should be.

Instead we need to educate the public that not all horses with lameness have significant abnormality, are suffering, need to be treated, cannot complete, etc.. My opinion is we do not have to change or redefine lameness, we just have to educate the public about what lameness is,” said Dr. Keegan, who is professor and director: E. Paige Laurie Endowed Program in Equine Lameness, College of Veterinary Medicine at the University of Missouri in Columbia.

MeV

For more information: van Weeren PR, Pfau T., Rhodin M, et al. Do we have to redefine lameness in the era of quantitative gait analysis? Equine Vet J 2017;49:567-569. http://onlinelibrary.wiley.com/doi/10.1111/evj.12715/full ModernEquineVet.com | Issue 9/2017

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CARDIOLOGY

NEW TREATMENT CALMS

Fluttering Hearts When traditional treatments for atrial fibrillation (AF) fail, cardiologists at the Cornell University College of Veterinary Medicine in New York can once again provide an alternative way to reset a horse’s arrhythmia back to its normal rhythm: transvenous electrical cardioversion (TVEC).

TVEC, which involves placing electrodes in the heart to reset its rhythm with an electric shock, was offered by the Cornell University Equine Hospital until about five years ago when the hospital could no longer purchase the catheters needed for the procedure. Recently, the catheters came back onto the market.

AF is the most common cause of irregular heartbeat in horses, especially among racehorses. AF occurs when the organized elec-

trical signals that normally control heart rate and contraction become disorganized, causing a rapid and erratic heartbeat. Horses can survive for years with AF, but the condition often causes poor performance.

Traditionally, veterinarians have treated AF with quinidine, a drug that can reverse irregular heartbeat in about 85% of treated horses. The drug has several possible side effects, however, and for horses that don’t respond well to quinidine, or that have had AF for several years, TVEC may be a better option.

TVEC works like the paddles of a defibrillator doctors use on humans, and even makes the horses “jump” from the muscle spasm.

But horses’ thick chest muscles

and lungs make it impossible to shock the heart from the outside; veterinarians place 3-foot-long catheters tipped with electrodes into the heart through the right jugular vein.

“The most difficult part of the procedure for us is to guide the catheter,” said Cornell cardiologist Romain Pariaut, DVM, DACVIM, DECVIM-CA. “In horses, it’s a long path to the heart from the outside.”

They use cardiac ultrasonography to monitor their progress and perform radiographs to verify the metal electrodes are sandwiching the right atrium. Finally, they anesthetize the horse, stand back, and apply a timed electric shock to return the heart to a normal rhythm.

In a recent case, Cornell veterinary students examined On-Star, a

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

Click here to watch video

Images courtesy of Cornell University.

19-year-old mare from the Cornell Equine Park teaching herd. “The students picked up the arrhythmia, and we diagnosed it as AF,” said Gillian Perkins, DVM, DACVIM, medical director of the Equine and Nemo Farm Animal Hospitals at Cornell, who coordinated the procedure.

On-Star’s procedure took approximately four hours and required a veritable village of clinicians: cardiologists, internists, radiologists, anesthesiologists and licensed veterinary technicians. Combined with the expense of the catheters, the initial diagnostic evaluation and hospitalization, the procedure costs $3,500 to $4,000.

“I’m very excited to be able to offer this procedure,” said Bruce Kornreich, DVM, PhD, DACVIM, associate director of the Feline Health Center and staff cardiologist at Cornell. “AF is a very common condition in horses that we’re often asked to diagnose and treat. This is another tool in our toolbox to convert these patients back to a normal heart rhythm.”

TVEC carries its own risks, not the least of which is associated with the general anesthesia. With this in mind, Drs. Pariaut and Kornreich tried to reduce the amount of time On-Star was under anesthesia through careful attention to electrode placement.

With TVEC and quinidine, there is also the possibility that horses will spontaneously go back into AF. One recent study found that between one-third and onehalf of horses successfully converted from AF to normal heart rhythm will revert after treatment.

So far, On-Star is doing well and has had no complications.

Funding from the Harry M. Zweig Memorial Fund and the large animal medicine and cardiology sections made TVEC possible for On-Star and for future patients diagnosed with AF. MeV

Transvenous electrical cardioversion (TVEC) involves placing electrodes in the heart to reset its rhythm with an electric shock.

ModernEquineVet.com | Issue 9 /2017

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NEWS NOTES

Storms May Cause Surge of Seasonal Pasture Myopathy Warn owners that storms with heavy winds could cause an unusual threat to horses: seasonal pasture myopathy (SPM).

In 2014, The United Kingdom saw a spike in cases of SPM after major storms, warned the British Equine Veterinary Association (BEVA)—the result of an increase in sycamore seeds.

Sycamore seeds appear in the autumn. They are toxic and can cause the fatal disease SPM, also called atypical myopathy. High winds from the tail ends of this very active hurricane season could cause the seeds to fall earlier than usual, so warn horse owners to take immediate steps now to identify sycamore trees on or near grazing land and prevent the seeds falling where they are in reach of horses.

BEVA recommended these steps: • Ideally move horses off pasture at times of risk.

• Restrict access to seeds by using temporary fencing.

• Ensure horses have access to good quality uncontaminated pasture.

• Provide consistent access to clean, palatable hay or haylage to minimize the risk of horses being tempted to ingest seeds.

• Do not fell trees, since doing so can lead to mas-

sive pasture contamination, further increasing the risks to horses.

• Discuss the risks and how to identify early clinical signs of SPM. • Be aware that a field without sycamore trees can still contain seeds spread by high winds or flood water.

SPM is a highly fatal muscle disease in horses caused by the toxin hypoglycin A, which is contained in tree seeds including that of the sycamore. While sycamore seeds may not be directly palatable to horses, those grazing on poor quality pasture may ingest considerable numbers of them. Horses kept in sparse pastures with an accumulation of dead sycamore leaves, dead wood and trees in or around the pasture and without access to supplementary hay or feed, are the most susceptible.

“In 2014 we saw a big spike in seasonal pasture myopathy in the aftermath of storms hitting the UK. It’s a terrible condition that can be fatal despite treatment.

It’s easier to spot the sycamore’s maple-shaped leaves now while they are still on trees. Otherwise the seeds may be confused with ash keys,” said Mark Bowen, senior vice president of BEVA. MeV

Photo courtesy BEVA

CLICK HERE TO READ ABOUT THE OUTBREAK OF SPM IN THE U.K.

Sycamore seeds

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Issue 9/2017 | ModernEquineVet.com

Sycamore trees

Making Sure Patients Are Safe on the Road Travel inherently increases the risk of infectious disease. Horse shows in particular are breeding grounds for environmental risks, cross contamination and higher-than-normal stress levels for horses.

These variables reinforce the need for veterinarians to provide horse owners with strong biosecurity guidelines and proper vaccination protocols, according to Craig Shoemaker, DVM, MS, Equine Professional Services Veterinarian at Boehringer Ingelheim, which makes several equine vaccinations. “The stress of trailering, traveling, being in a new environment and/or working competitively takes a toll on a horse’s immune system,” he said, adding that veterinarians are in a unique position to provide preventative counsel to horse owners.

Dr. Shoemaker suggested that veterinarians share these tips

1. CLEAN AND DISINFECT STALLS Before unloading horses, stalls should be inspected for any remaining bedding or fecal matter, which should be removed and disposed of. Walls should be washed down with a good detergent or cleaning agent, then sprayed with a disinfectant, such as a 1:10 dilution of bleach and water. Other good disinfectants are available.

Pre-Show Countdown

3. PREVENT NOSE-TO-NOSE CONTACT “These diseases are spread three ways,” notes Dr. Shoemaker. The primary route is horse-to-horse or noseto-nose contact. For instance, “In the practice ring, horses should not be tied to the fence where there is potential for contact with other horses walking by.”

Vaccination is the first consideration. The American Association of Equine Practitioners (AAEP) recommends vaccinating horses against five core diseases: rabies, tetanus, West Nile Virus, and western and eastern equine encephalitis. In addition, horses need to be vaccinated for equine influenza virus and equine herpes virus within six months of attending a United States Equestrian Federation (USEF)-sanctioned horse show. For a complete list of USEF-required vaccines, click here.

“It is paramount that horses are vaccinated for equine influenza and equine herpes as both can be the cause of acute respiratory disease, especially in horses that experience the stress of travel and showing” Dr. Shoemaker said. “For a traveling horse under high stress, modifying vaccination protocols to include increased frequency of vaccination for equine herpes may be needed.”

Because the equine influenza virus changes over time—just like the human influenza virus—using an updated vaccine that provides direct protection will complement the respiratory vaccination protocol, he explained. Veterinarians should also discuss vaccination against other non-core diseases, such as strangles or equine rhinitis following a risk analysis.

A baseline temperature should be taken and recorded for each horse before leaving for the show, and temperatures should be monitored daily while at the show, as a sudden spike can be one of the first signs of a problem.

It is important for your clients to understand that diseases are easily spread from horse to horse and from equipment and facilities to horses. The following steps will help them to provide maximum protection:

2. AVOID CONTAMINATED WATER All water buckets should come from the horse owner’s home. Do not allow horses to drink from any containers provided by the showgrounds, including communal water tanks. Avoid cross-contamination by not allowing hoses to touch water or buckets when being filled.

4. USE ONLY YOUR OWN EQUIPMENT The second route of infection is through contaminated fomites. With multiple horses, be sure each one has its own set of equipment, including a water bucket, that is used exclusively for that individual. “It’s less of an issue among horses from the same barn, but it’s one other variable,” Dr. Shoemaker notes.

5. PRACTICE GOOD HAND HYGIENE The third route of infection is human hands. “People are often the culprit in spreading diseases,” Dr. Shoemaker said. When moving from horse to horse, wash hands between contact. “I recommend a lot of hand sanitizer,” he adds.

6. MONITOR HEALTH AND BEHAVIOR A horse’s temperature should be taken twice a day— in the morning and evening and recorded in a log. A spike in temperature may be the first way to identify a potential problem. The individual should be isolated, and a protocol developed to limit exposure to other horses. Other signs of a potential problem are being off feed, displaying a quiet attitude, or developing a cough, runny nose or watery eyes.

When returning to the barn, a plan should be in place to segregate the horse that traveled from the rest of the barn for two weeks.

MeV ModernEquineVet.com | Issue 9/2017

15

TECHNICIAN UPDATE

Iron Will

Shutterstock/lembi

By Heather Hopkinson RVT, VTS-EVN

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William presented to the North Carolina State University Equine Emergency Service as a 5-day-old Corolla horse colt on June 17, 2015 at 7:30 pm for evaluation and treatment of bradycardia, dyspnea and severe lethargy.

William is from the wild Corolla herds on the Outer Banks of North Carolina. His foaling, which occurred on 6/12, was not witnessed, but he has always been especially small. He was noted to be acting somewhat depressed when he was checked over the weekend, and was nursing poorly (he was able to latch on and swallow, but would only suckle a few times before stopping).

His dam is reportedly very healthy, with a body condition score of 6 and a healthy coat. William was seen to be drinking from the canal over the weekend (brackish water with a salinity of 2%). He appeared to be deteriorating and the dam was beginning to show less and less interest in him.

He was removed from the herd at 9 am and taken to the referring veterinary clinic for further evaluation where he was found to be very lethargic and moderately dehydrated. His heart rate was 48–52 beats per minute

Issue 9/2017 | ModernEquineVet.com

and his respiratory rate was 15 breaths per minute. He was also noted to be dribbling urine.

About 185 ticks were removed at that time. An IgG indicated adequate passive transfer (IgG >800). He was given 9–10 oz. of Pedialyte electrolytes, as well as fluids, dextrose and epinephrine, which improved his heart rate to between 60 and 70 bpm. He was also administered intranasal oxygen. After initial stabilization he was referred to NCSU CVM for further workup and treatment. On the truck ride from the referring veterinarian, he was given molasses and 4 oz. of Pedialyte from a syringe. His heart rate remained around 60 bpm during the transfer. On presentation to the NCSU CVM, William’s initial physical examination findings were a temperature 94.7° F, pulse 72 bpm, respiration 15 breaths per minute, and a body condition score of 4/9, mucous membranes pink, capillary refill time: 2 seconds. Both eyes were clear, and there was airflow from both nostrils with no evidence of nasal discharge. No arrhythmias or murmurs were appreciated.

Digital pulses were within normal limits but his distal extremities were cold. A full neurologic exam was not performed, but he appeared to be depressed, weak and he was nonambulatory. A weak and inconsistent suckle reflex was observed and his palpebral reflex was intact. His joints palpated within normal limits. There was no urine from his umbilicus when he leaked urine

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• A three course, 10 module, equine-only online program offered through ACT • Geared toward Credentialed Veterinary Technicians, Assistants, Support staff, & Students • Areas of study include: equine medical terminology, anatomy and physiology, parasitology, laboratory, diagnostics, equine basics (breeds, wellness, husbandry,) diagnostic procedures, emergency medicine, restraint, pharmacology, surgical assistance and anesthesia, equine office procedures • A certificate of completion is awarded to those who: Successfully complete required courses Complete the list of required skills (per a supervising DVM who is an AAEP member) Attend an AAEVT regional CE symposium and participate in the we labs • Those individuals who successfully complete the programs will be recognized as AAEVT Certified Equine Veterinary Technicians / AAEVT Certified Equine Veterinary Assistants depending on their current designation. The certificate is recognized by the AAEVT and the AAEP but does not grant the credentialed status by the AVMA • For more information go to www.aaevt.4act.com or call 800-357-3182

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Fo r m o re i n f o r m a t ion v ist w w w.a ae vt.or g

*American Association of Equine Veterinary Technicians and Assistants

TECHNICIAN UPDATE

The colt appeared to be deteriorating and the dam was beginning to show less interest in him. He was found to be very lethargic and moderately dehydrated. in recumbency. He had a dull hair coat with multiple ticks attached. Initial diagnostic evaluation findings included blood glucose at 53 mg/dL. Arterial blood gas revealed pH 7.36, pCO2 38 mmHg, pO2 48 mmHg, and lactate 1.7 mmol/L. Serum chemistry revealed moderately elevated BUN (71 mg/dL), moderately elevated AST (857 U/L), moderately elevated CK (7740 U/L), and all other values were within normal limits.

Thoracic ultrasound showed small areas of consolidation over the right cranial lung and moderate consolidation in the caudal lung, which was the down lung during IV catheter placement. Thoracic radiographs revealed moderate generalized cardiomegaly with no evidence of pulmonary edema.

Cardiac ultrasound revealed poor contractility (fractional shortening ~22%), no evidence of ventricular septal defect or any other congenital lesion, and no evidence of pericardial effusion. Blood pressure upon arrival was 100/64 mmHg. Abdominal ultrasound revealed enlarged umbilical artery and vein with multiple pockets of fluid within a ruptured urachus and the bladder appeared to be intact.

Normal motility was observed in the gastrointestinal tract. An abdominocentesis was obtained and a strawcolored, serous fluid with an electrolyte profile that is consistent with urine was observed. William was bradycardic, dyspneic, hypoglycemic, hypothermic, anemic, hypotensive and severely lethargic. An arterial blood gas was obtained and revealed moderate hypoxemia.

Nasal oxygen was initiated. An IV long-term double lumen catheter was placed and IV fluids containing REFERENCE TABLE FOR BLOOD WORK (Ranges)

18

Arterial pH

7.41–7.50

Arterial pCO2 (mmHg)

32–40

Arterial pO2 (mmHg)

91–100

BUN (MG/DL)

7–25

AST (IU/L)

202–338

CK (IU/L)

117–564

Platelet Count (x10^3/UL)

99–277

GGT (IU/L)

4–19

SDH (IU/L)

6.3–13.8

Issue 9/2017 | ModernEquineVet.com

calcium and dextrose were administered. Due to deterioration of the bradycardia during his work up, he was administered epinephrine, and placed on a dobutamine CRI to improve his contractility and cardiac output. A nasoesophageal feeding tube was placed to provide nutrition. Radiographs were taken to confirm placement of the tube into the stomach and J5 plasma was administered intravenously to help treat potential sepsis, and caffeine tablets per rectum were added to stimulate respiration, as well as a doxapram CRI IV was started.

He was placed on a high dose of ceftiofur IV. A urinary catheter was placed to help prevent the bladder from filling and aggravating the uroabdomen. Urine specific gravity was monitored closely and fluid rate was increased or decreased based on these and blood pressure measurements. Electrolytes were added as needed based on serial electrolyte monitoring. William consistently had good urine output, normal USG’s and normal kidney values on bloodwork.

On June 19, a second echocardiogram was completed to clear William for surgery to correct his patent urachus. A third echocardiogram was performed on the same day to investigate a grade 3 systolic heart murmur.

The cause for the murmur could not be visualized, but was likely due to a small PDA that had yet to close. It was revealed that his heart contractility had increased and was within normal limits. William was taken to surgery on the evening of June 19 to correct his uroabdomen and remove the umbilical structures. He recovered uneventfully from surgery and the urinary catheter remained in place as long as he was recumbent.

William had moderately elevated muscle enzymes on admission, and was administered both vitamin E and selenium to treat a potential deficiency. Blood samples for both vitamin E and selenium were submitted and were within normal limits. Six days after admittance, William was noted to be thrombocytopenic (62,000 platelets/UL). His antibiotics were switched to potassium penicillin and amikacin due to the potential for certain cephalosporins that produce an immunemediated thrombocytopenia.

His platelets continued to decrease the following day, but then gradually began to increase, and were found to be within normal limits on June 29. William was weaned off dobutamine, doxapram and IV fluids within

NEWS NOTES

About the author

Heather graduated from Central Carolina Community College, Sanford NC with an AAS in Veterinary Medical Technology in 2006.

She is a Registered Veterinary Technician at North Carolina State University—CVM, Farm and Equine Medical Center in Raleigh. In 2011, Heather was part of the first class that successfully passed their AEVNT Exam and became a Veterinary Technician Specialist— Equine Veterinary Nursing. She is currently the president of the Academy of Equine Veterinary Nursing Technicians and vice-president of the North Carolina Association of Veterinary Technicians.

Horses Masticate Similarly to Ruminants Herbivores digest their food much better if it has been strongly fragmented by intensive mastication. For ruminants such as cows, sheep, goats, deer, llamas or camels, eating and ruminating are two different processes: Some time after feeding, they regurgitate part of their food and chew it again with particularly even, rhythmic movements.

In this way, they achieve the maximum degree of Mastication halters record the movements of the mouth and automatically differentiate between eating and fragmentation of their food. ruminating Researchers of the University of Zurich and the Swiss Federal Institute of Technology Zurich (ETH Zurich) are now investigating whether the chewing movements of the ruminants are similar to those of other herbivores. In their study with horses, cows and camels, they use special mastication halters, which can record the movements of the mouth and automatically differentiate between eating and ruminating.

In the case of cows and camels, the mastication rhythms differ clearly. The movements during eating were much more irregular than those during rumination, and camels generally have a lower chewing rate during ruminate than cows. The situation is different for horses: "Much to our surprise, the evaluation software determined that horses do not eat, but rather ruminate," said Marie Dittmann, doctoral student at the University of Zurich and ETH Zurich. "Although horses are not ruminants, they fragment their food with the same rhythmic chewing movements as cows do during rumination."

For Marcus Clauss, Dr Med Vet, MSc, DECVCN, professor at the Clinic for Zoo Animals, Exotic Pets and Wildlife of the university, the similarity in the chewing rhythm of such different animal groups is understandable: "Horses do not have a second chance to re-chew something that is hard to digest. For that reason, they have to masticate very thoroughly when eating. That obviously works best with rhythmic and even movements."

Credit: UZH

six days after admittance. His feeding tube was pulled on June 24 and attempts were made to teach William how to drink milk from a pan. Attempts were unsuccessful. On June 25, a nurse mare was obtained but ended up being too tall for William to be able to nurse.

On June 26, another nurse mare was obtained from the NCSU Theriogenology Service.

William immediately accepted the mare and started nursing. Recheck chemistry on June 25 showed an elevated GGT (78 u/L). Repeat hepatic panels showed elevated GGT measurements that continued to increase from 78 up to 145 u/L. His SDH went from 25.5 IU/L to 107.4 IU/L. No abnormalities were noted on abdominal ultrasound. A liver biopsy was performed for histopathology and culture. The culture came back negative. Biopsy results revealed PAS positive vacuolar hepatopathy, consistent with glycogen accumulation.

Differentials at this point were glycogen branching enzyme deficiency (although not fitting with the clinical picture), steroid hepatopathy, congenital or idiopathic.

Baseline cortisol was measured and found to be within normal limits. William was switched to oral antibiotics (cefpodoxime) on June 28. Thoracic radiographs were taken on June 29 due to his increased respiratory rate and a mild elevation in temperature. Radiographs revealed bronchopneumonia likely due to aspiration. He continued to improve clinically.

On July 7, his liver enzymes were rechecked and his SDH was within normal limits while his GGT was still elevated at 137 IU/L. William was switched to oral doxycycline on July 8. He continued to improve clinically, gaining weight and getting stronger every day. On July 13, a recheck hepatic panel revealed a GGT of 78 IU/L and all other parameters were within normal limits.

William was discharged on July 15 with instructions to monitor his liver enzymes weekly until they were within normal limits.

MeV

Irregular chewing protects the teeth That begs another question: Why do cows chew differently when eating? The researchers have an interesting theory: When grazing in the wild, herbivores also take in dust, dirt or earth, which additionally abrades the teeth while eating. Horses have to put up with this problem. Ruminants, on the other hand, can postpone thorough mastication after the initial eating process until later after the food has been cleaned of such contamination in the rumen. Less tooth abrasion results during eating due to less intensive chewing.

"The irregular ingestive mastication of cows could therefore have developed in order to MeV protect the teeth while eating," Clauss said.

For more information: Dittmann MT, Kreuzer M, Runge U, et al. Ingestive mastication in horses resembles rumination but not ingestive mastication in cattle and camels. Journal of Experimental Zoology Part A: Ecological and Integrative Physiology, 2017; DOI: 10.1002/jez.2075 ModernEquineVet.com | Issue 9/2017

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