The Modern Equine Vet - March 2021

The Modern

Equine Vet www.modernequinevet.com

Vol 11 Issue 3 2021

How to Conduct a Foal Neuro Exam in the Stable Patch ECG for Long-Term Cardiac Monitoring Is More REHIP Better for R. equi?

What's the Evidence for Laminitis Treatments?

TABLE OF CONTENTS

COVER STORY

4 How to Conduct a Neuro Assessment of the Foal Cover: Shutterstock/Pavlina Trauskeova

ASK THE INFECTIOUS DISEASE EXPERT

What’s the Best Way to Respond to Clients Who Want Serological Titers Before Vaccinations?............................................................................3 DENTISTRY

Dental Exams: Help Your Clients Realize Their Importance to Horse Health.................9 CARDIOLOGY

Patch ECG Compares Well to Conventional Monitor for Long-Term Cardiac Tests.............10 INFECTIOUS DISEASES

2 L of REHIP More Effective Than 1 L, Study Shows.............................................................12 LAMINITIS

An Evidence-Based Look at Multimodal Laminitis Treatments.....................................14 NEWS NOTES

Ethanol Useful for Aseptic Distal Limb Prep...........................................................................8 OA of Caudal Cervical Region Common in Warmbloods.................................................17 ADVERTISERS Merck Sponsored Content..................................................................................3 American Regent Animal Health/Adequan...................................................5 Epicur Pharma......................................................................................................7 Zoetis Sponsored Content..................................................................................9

MG Biologics........................................................................................................11 Zoetis/iStat..........................................................................................................13 Merck Animal Health........................................................................................15

The Modern

Equine Vet SALES: Matthew Todd • Matthew Gerald EDITOR: Marie Rosenthal ART DIRECTOR: Jennifer Barlow CONTRIBUTING WRITERS: Paul Basillo • Adam Marcus 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 3/2021 | ModernEquineVet.com

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ASK

THE

Infectious Disease Expert This column, brought to you by Merck Animal Health, features insightful answers from leading minds.

What’s the best way to respond to clients who want serological titers before vaccinations?

T

he simple answer is that, for core diseases, veterinarians must recAT A GLANCE: ommend vaccination schedules Serology titers in horses with known that follow the vaccine labels. One exvaccine reactions* ception may be a horse that has previously Rabies, tetanus Serum antibodies likely correlate experienced a severe vaccine-associated with protection and may be useful adverse event (VAAE) and risk of another in horses that have previously reaction may be more life-threatening than experienced a severe VAAE the disease itself. To reduce overall risk, EEE/WEE, WNV Serologic correlates for protection measuring a specific antibody titer may help not well established; Annual or biyou access the patient’s immunological staannual revaccination recommended tus and provide guidance in determining regardless of titer whether the horse is protected. If the results EIV, EHV Serum antibody levels not well indicate the horse has antibody levels sugcorrelated with protection and gestive of protection, you could reasonably cannot be recommended to predict recommend delaying revaccination. need for vaccination This explanation works well for ra*For a complete reference tool, refer to the AAEP bies and tetanus. For these pathogens, Guidelines for Serology in Horses with Adverse Events antibodies in the blood appear to be the from Vaccination. main correlate for protection, which may reflect acquisition by “injection”– rabies through a bite and tetanus through puncture the label). This may influence quarantine wounds. Studies show that horses maintain and other measures if a horse is exposed to antibody levels thought to be protective rabies or bites someone. against rabies and tetanus for at least three years after revaccination.1,2 So, if serologic SEROLOGY RESULTS testing shows antibody levels that should DON’T ALWAYS APPLY be protective against rabies or tetanus, you Using titers to predict protection against Eastcould delay revaccination in reactive horsern/Western equine encephalomyelitis (EEE/ es and recheck serum antibodies in a year.

WEE) and West Nile virus (WNV) is not well Remember that from a public health standjustified. Serum antibody levels can show point, a horse is not considered “properly whether the horse has responded to vaccinavaccinated” against rabies unless it has been tion, but levels needed to correlate with provaccinated within a year (i.e., according to tection are not clear cut. Even after natural in-

fection, immunity is unlikely to last much more than a year. Since EEE/WEE and WNV are prevalent and carry high mortality, vaccination per the label is recommended regardless of the levels of antibodies in the blood, especially in regions with year-round mosquito activity.

For risk-based diseases, such as equine influenza virus (EIV) and equine herpesvirus (EHV), serology titers are even less relevant in predicting protection. Duration of immunity is short and, since these diseases are transmitted through the respiratory tract, protection is better correlated with local immune responses than with blood antibody levels when using the tests available in North America.

Serum antibodies are not a good predictor of protection against strangles; however, measuring them can help avoid vaccinating a horse that may be at risk of developing purpura hemorrhagica. Horses with high antibody levels against Streptococcus equi are more likely to develop purpura hemorrhagica after strangles vaccination.

TAKE-HOME MESSAGE When horse owners ask about pre-vaccination bloodwork, briefly explain the above considerations to help them understand what makes sense for their horse. The conversation will help them trust your recommendations and, most importantly, help you ensure horses are properly protected.

1. Harvey AM, Watson JL, Brault SA, Edman JM, Moore SM, Kass PH, Wilson WD. Duration of serum antibody response to rabies vaccination in horses. J Am Vet Med Assoc. 2016 Aug 15;249(4):411-8.

2. Kendall,A, Anagrius K, Ganheim A, Rosanowski SN, Bergstrom K. Duration of tetanus immunoglobulin G titers following basic immunization in horses. Equine Vet J 2016 Nov;48(6):710-713.

ABOUT THE AUTHOR W. David Wilson, BVMS, MS, HonDACVIM, is a professor emeritus of equine medicine in the Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, where he was a faculty member for 36 years. A prolific writer and speaker, Dr. Wilson has served on many AAEP committees and task forces. He continues to be active in research and is the North American co-editor for the Equine Veterinary Education journal.

WANT TO ASK A QUESTION? EMAIL THE EDITOR. For more infectious disease-related information, visit merck-animal-health-equine.com/programs

Copyright © 2021 Intervet Inc., d/b/a Merck Animal Health, a subsidiary of Merck & Co., Inc. ModernEquineVet.com | Issue 3/2021

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NEUROLOGY

How to Conduct a Neuro Assessment OF THE NEONATAL FOAL M a r i e

R o s e n t h a l ,

M S

A neurological examination of the neonatal foal with a physical examination provides a more comprehensive assessment of the young horse, according to Monica Aleman, MVZ Cert., PhD, DACVIM (LAIM & Neurology), a neurologist at the University of California-Davis, School of Veterinary Medicine.

The neurologic examination should assess behavior, state of consciousness, cranial nerves, spinal reflexes, posture and gait, she said, and in the stable, can be done using simple tools in every veterinarian’s toolbox: listening, observation, palpation and patience.

Although it does not matter in which order the examination is performed, she said it was a good idea to develop a routine so that nothing is overlooked.

The goals of the neurological exam are to determine whether the foal is meeting its neuroanatomical milestones, and if not, why not.

Because a horse is a prey animal, the normal transition from intrauterine to extra-uterine life must develop quickly in the foal. Important early milestones include the time to sternal recumbency, when the foal becomes alert and responsive to stimuli, the suckle reflex, nickering in response to the mare, the time it takes to stand and to nurse.

A modified APGAR score can be calculated in the stable; monitoring the heart and respiration rates, mucus membrane color, muscle tone, and the response to several stimuli will quickly indicate if the foal has a neurological issue that requires immediate attention.

During the evaluation, the veterinarian should ob4

Issue 3/2021 | ModernEquineVet.com

serve behavior and the animal's state of consciousness, cranial nerves and the foal’s responses, reactions and Signs of a problem in medium reflexes, segmental reflexes oflevel thedressage spine,horse posture, in right gait canter: Earstime back; intense and nociception, if needed. “The only we're stare; going and the bit is pulled through to to evaluate for nociception, however, the right. is if the animal is non-ambulatory, and there is no obvious voluntary movement. If the animal is walking, you don't need to check for this,” Dr. Aleman said.

Behavior

A new foal should be curious and responsive to its environment. It should be investigating, licking and smelling, while bonding with its mother, answering her nickers and suckling. That is normal behavior.

If a light is shone in its eye, it should blink. Check the direct pupillary reflex, which is a response to light that enters the ipsilateral eye and consensual pupillary reflex that responds to bright light shown in the contralateral eye.

Foals should respond to external stimulation with exaggerated movements. Again, in the field, she uses a common tool—she claps. The foal should jerk its head up in response to the sudden noise. “That is normal.

This is a remarkable evolutionary adaptation of the foal in order to survive in the wild—the foal is fully hearing and visual,” Dr. Aleman said.

To check the spinal reflexes, the animal must be completely relaxed and be in lateral recumbency. A foal should enter a relaxed state when restrained gently. “If it’s standing, it is going to have increased muscle tone,” she said. “Even if he’s recumbent, he must be relaxed.

Shutterstock/DasyaDasya

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Reduce inflammation Restore synovial joint lubrication Repair joint cartilage Reverse the disease cycle When you start with it early and stay with it as needed, horses may enjoy greater mobility 2, 4, 5 over a lifetime. Discover if Adequan is the right choice. Talk to your American Regent Animal Health sales representative or call (800) 458-0163 to order.

BRIEF SUMMARY: Prior to use please consult the product insert, a summary of which follows: CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. INDICATIONS: Adequan® i.m. 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. CONTRAINDICATIONS: There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. WARNINGS: 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. PRECAUTIONS: The safe use of Adequan® i.m. in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. For customer care, or to obtain product information, visit www.adequan.com. To report an adverse event please contact American Regent, Inc. at (800) 734-9236 or email pv@americanregent.com.

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www.adequan.com 1 Data on file.

2 Adequan® i.m. Package Insert, Rev 1/19.

3 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.

4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57.

5 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse.St. Louis, MO: Elsevier, 2016; 33-48.

All trademarks are the property of American Regent, Inc. © 2020, American Regent, Inc. PP-AI-US-0372 02/2020

NEUROLOGY

APGAR SCORE Measure Heart rate Respiration Mucous membranes Muscle tone Responsiveness

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If he's recombinant, but all rigid, touch or noise, there is something IMPORTANT MILESTONES you're going to have a false interwrong,” Dr. Aleman said.

Milestone Time pretation of the reflexes, or maybe A foal that is obtunded will you are not going to even be able to Sternal recumbency 1–2 minutes respond to tactile and audio check the reflexes.” stimuli; a foal in stupor will only Alert and responsive to 5 minutes She gently taps 3 areas of the be aroused by very painful stimuli stimuli thoracic limbs: biceps, triceps and only for as long as that stimSuckle reflex 20 minutes and flexor; 3 aspects of the pelvic ulus is applied. “That is the big Nickering in response 30 minutes limbs: patellar, gastrocnemius and difference between a stupor and to dam’s nickering flexor; and the cutaneous trunci. a severely obtunded foal. The obStanding 1 hour The foal will have crossed extunded foal is going to respond to Nursing 2 hours tensor reflexes; if 1 limb is flexed, non-painful stimuli and the foal in the contralateral limb will extend stupor, very painful stimuli. And and vice versa, according to Dr. Aleman. “These foals in coma, the foal is not going to be arousable under any lose that cross extension as they mature,” she said. circumstances, not even to very painful stimulate.”

She also gently checks the anal and perineal reflex.

Dr. Aleman gave some pointers to localize com“When you lightly tap the anal sphincter, you should mon neurological problems in the foal. First, figure out see clamping of the tail and constriction of the anal which part of the brain is at fault. sphincter,” she said.

Check its posture during stance and urination, she Cerebral Cortex and Thalamus said. “Foals usually have a wider stance, but as they The thalamus translates neural impulses from varimature, they stand a little bit more square,” she said. ous receptors to the cerebral cortex, which is responAn abnormal stance might not be an indication sible for awareness and mental activities. Barking or of a neurological problem. It could signal abnormal some other type of compulsory vocalizing or other growth of the hoof, she said. compulsory behavior, star gazing and seizures, are The gait is important, she said. Evolution dictates among the signs of a problem in this part of the the foal should be fairly coordinated shortly after brain, as are sudden behavioral changes. If the anibirth to escape a predator. “These foals usually have a mal is usually aggressive and suddenly becomes subbouncy gate as neonates, but that bouncy gate usually dued or is very docile and suddenly becomes aggresis lost as they mature,” she said. sive, that could be a signal of a problem in this area.

Cortical blindness, seizures, proprioceptive deficits What’s Wrong? and altered motor function can also be signs.

“If the foal is quiet and obtunded, in lateral recum“They can have 1 sign, 2 signs, 3, or all of these,” she bency and not responding to external stimuli, such as said. “But just having 1 of these signs is enough to localize to this area.”

She elaborated a bit on seizure activity. “We could have extracranial causes of seizure or intracranial Normal Abnormal causes,” she explained. She discussed a case of an orphan with an extracranial cause. The owner prepared Regular, 60 beats per minute Undetectable, the milk replacement for the foal, but made an error in irregular, or ≥60 bpm. the preparation and the milk contained too much salt Regular, 60 respirations per minute Undetectable, causing hypernatremia. irregular, or ≥60 rpm There are many causes for motor disorders, includPink Blue, bright red or ing neuroglycopenia, which is a shortage of glucose yellow in the brain, typically from hypoglycemia. This will often accompany hypernatremia, which is an electroStrong enough to be in sternal recumbency lyte imbalance. Even though the foal is recumbent, • Nasal stimulation (expected Not responding to the joints are not the problem, and they are not conresponse: strong grimace, sneeze); stimuli tracted, yet, the foal will remain recumbent and will • Ear tickle (expected response: head not initiate movement and doesn’t stand, she said. shake) and “So that is a big clue—you have all the apparently • Back scratch (expected response: normal functions there, but it is simply not happening. attempts to stand) So that is another big red flag for disease,” she said.

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Brainstem Disorders

The brainstem controls many basic functions of the nervous system in the horse. There are multiple issues that can be affected by the brainstem, including altered states of consciousness: obtundation, stupor and coma.

There are also multiple cranial nerve deficits, such as sleep disorders, central vestibular disease, cardiovascular, respiratory and proprioceptive deficits. The prognosis for cardiovascular and respiratory disorders associated with the brainstem are poor, she said.

Foals can have 1 or more signs if they suffer from cranial nerve deficits. Often cranial nerve deficits will be accompanied by an altered state of consciousness. .

Abnormal sleep can also be a signal, she said. A slow wave sleep in a foal occurs when the foal is lying down.

“The foal should never sleep standing. The neonatal foal does the entire sleep in recumbency,” she said. “So this is very abnormal to see a foal standing and sleeping,” she said. “As they mature, they will start sleeping more like the adult horse by 2 or 3 months of age.”

Cerebellum Disorders

The cerebellum controls movement and motor control.

Signs of cerebellum disorders are hypermetria, ataxia, intention tremors, lack of menace, anisocoria and proprioceptive deficits. A foal with cerebellar hypoplasia is born with a small cerebellum compared with a normal foal. Although different from cerebellar atrophy, both diseases will have the same clinical signs: depressed or absent menace reflex and ataxia without weakness.

Intention tremors occur during intended movement. The animal will experience tremors, usually of the face or head, when it tries to move, walk or eat.

Cerebellar tremors are not intention tremors.

A common problem is vestibular disease. Signs include a head tilt, nystagmus, ventral strabismus, leaning, circling and ataxia. “These are the common clinical signs that you could see with either peripheral or central vestibular disease,” she said.

Animals with vestibular disease rely on visual input, she said. If you remove the visual input, say by putting a towel over the animal's face, it’s defects will be obvious. “You will definitely be able to tell if the animal has vestibular disease because the change will be quite dramatic.” She said.

“The majority of the cases you're going to see out

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NEUROLOGY

on the field, I would say probably 99% of the cases that you are going to see with vestibular disease are going to be ipsilateral to the site of the injury,” Dr. Aleman said.

Ipsilateral vestibular disease usually affects 1 side of the brainstem; paradoxical, the caudal cerebellum.

Vestibular disease that is affecting the peripheral nerves is ipsilateral. She offered some tips to tell central versus peripheral disease: Looking at nystagmus will be helpful, she said. If the head is moved to different positions, it changes in central disease, but not in peripheral disease.

The state of consciousness is another indicator, she said. “Even if the animal is bright and alert, it doesn’t rule out a central problem, but if it's obtunded, has stupor or coma, there is central vestibular disease.”

Although facial nerves could be affected by either because the facial nerve and vestibular nerve pathways are close, if there are multiple cranial nerve abnormalities, it’s going to be associated with central vestibular disease.

Signs of spinal cord dysfunction could be sensory or motor, depending on what parts of the spinal cord are affected. Sensory deficits include proprioceptive ataxia or proprioceptive deficits; motor issues include dysmetria, paresis and paralysis and weakness. Motor

deficits can be caused by an upper motor neuron injury or a lower motor injury. Another spinal problem are compressive myopathies, which can occur at various areas along the spinal cord.

Unfortunately, proprioceptive deficits can be affected by every brain region, she said. “So that means that proprioceptive deficits alone cannot help you to localize the disease. You have to see what other signs you have,” she said.

The neuromuscular junction can be involved in many functional and physical deficits, including paresis, paralysis, dysphagia, dysphonia, dyspnea, proprioceptive deficits, gait deficits, reflex deficits and muscle atrophy, she said.

Once a neurological problem has been determined, the animal requires a complete diagnostic work up, which should be tailored toward the specific signs the foal is having. Full blood work, urinalysis, electrolyte analysis and other tests will be required. Cerebrospinal fluid might be needed for certain problems. Imaging will also be helpful, radiography and ultrasonography can be easily performed in the field, she said, but advanced tests such as electroencephalography will need to be done at a large academic institution.

MeV

Ethanol Useful for Aseptic Distal Limb Prep Ethanol can be used to prepare the skin before performing immediate, short procedures in horses, according to a recent study.

This randomized trial aimed to determine whether ethanol-based antisepsis reduces bacterial counts on the equine distal limb comparable to a current chlorhexidine scrub method and determine the most effective application technique for the product.

They studied 41 horses, and each horse had a 5 x 5 cm patch clipped over the distal interphalangeal joint of 3 limbs. By horse, each limb was randomly assigned to a treatment group: 1. 5-minute scrub using 4% chlorhexidine gluconate to a clipped site (CHG); 2. 90-second scrub using 80% ethanol to a clipped site (ETC); 3. 90-second contact with 80% ethanol applied as a spray to a clipped site (ETS); and

4. 90-second scrub using 80% ethanol to an unclipped site (ETUC).

Samples were collected pre- and post-treatment and plated in duplicate. Bacterial counts were log10 transformed and averaged between duplicates. Mean log10 colony forming units (CFU) reduction was compared among the groups. There was no significant difference in mean log10 CFU reduction between CHG and ETC in either fore- or hindlimbs. In forelimbs, there was no significant difference in mean log10 CFU reduction among any groups. In hindlimbs, CHG had significantly greater mean log10 CFU reduction than ETUC and ETS. A 90-second wet contact time using gauze sponges was recommended. In addition, the researchers noted that the study did not investigate the efficacy of other alcohol-based antiseptics such as isopropanol or n-propanol.

MeV

For more information: Doyle AJ, Saab ME, Lewis KM, et al. Comparison of chlorhexidine and alcohol-based antisepsis of the distal limbs of horses. Equine Vet J. 2020 Dec. 31 https://doi.org/10.1111/evj.13417 https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13417 8

Issue 3/2021 | ModernEquineVet.com

SPECIAL ADVERTISING SECTION

Dental Exams: Help Your Clients Realize Their Importance to Horse Health As a veterinarian you can tell a lot from these regular checks

By Jeff A. Hall, DVM, Senior Veterinarian, Equine Technical Services, Zoetis

A

2019 equine dental study, published in the Journal of Equine Veterinary Science, revealed there is an established link between common horse behavior problems and abscessed cheek teeth. Periapical infections in cheek teeth are common in horses1 and will usually induce pain that horses then exhibit in their behavior.

schedule annual dental exams because they are unsure about what goes into an exam and what their horse will experience. Veterinarians have an opportunity to educate horse owners about the importance of dental exams, and the impact dental challenges can have on their horse’s well-being and behavior.

Despite this established connection between dental pain and behavior problems, many horse owners are unaware of the impact dental challenges can have on their horse’s health and performance. A 2020 equine dental wellness survey conducted by Zoetis revealed that out of nearly 4,000 horse owners from across the U.S., 73% indicated their horse was showing at least 1 behavior associated with dental pain.2 Yet 22% of respondents indicated their horse hasn’t had a dental exam in at least 12 months.2

Take the time to follow up with clients who haven’t brought their horse in for a dental exam. Reassure clients that dental exams are safe, routine procedures for their horse by helping them know what to expect. This includes how long the exam will last and what you’re looking for as you examine their horse. As part of this conversation, explain that in order to complete a thorough visualization and palpation of the mouth and teeth, the horse must be sedated. Sedation helps ensure compassionate care for the horse and precise control for the veterinarian performing the procedure.

I find that horse owners sometimes hesitate to

HELP CLIENTS KNOW WHAT TO EXPECT DURING DENTAL EXAMS

SEDATION FOR A SAFE DENTAL EXAM Sedation isn’t only for the horse’s safety. It’s also for the safety of you, your technician, or anyone handling the horse. A consistent, reliable sedative is preferred — one that provides pain control to help ensure the horse’s comfort throughout the exam is also advantageous.

in just 1 dose. It’s supported with 30 years of safety data and provides the veterinarian with predictable sedation.3 And veterinarians continue to rate DORMOSEDAN highest of all equine sedation products for reliability.3 Learn more about it by visiting Dormosedan.com.

DORMOSEDAN® Sterile Solution (detomidine hydrochloride) meets equine sedation and analgesic needs

SCHEDULING DENTAL EXAMS IN SPRING WELLNESS EXAMS Remind your clients that spring

physical exams are the perfect time to complete a full wellness check that includes a dental exam, vaccination against the five core (potentially fatal) diseases and risk-based diseases as needed, as well as a fecal exam followed by the appropriate deworming administration. Just like vaccinations and parasite control, a thorough dental exam helps set horses up for a successful and healthy year.

IMPORTANT SAFETY INFORMATION: Do not use DORMOSEDAN STERILE SOLUTION in horses with pre-existing atrioventricular (AV) or sinoatrial (SA) block, with severe coronary insufficiency, cerebrovascular disease, respiratory disease, or chronic renal failure. Intravenous potentiated sulfonamides should not be used in anesthetized or sedated horses. Careful consideration should be given to horses approaching or in endotoxic or traumatic shock, to horses with advanced liver or kidney disease, or to horses under stress from extreme heat, cold, fatigue, or high altitude. Do not use in horses intended for human consumption. Handle dosing syringes with caution to avoid direct exposure to skin, eyes or mouth. See full Prescribing Information.

REFERENCES 1 Pehkonen J, Karma L, Raekallio M. Behavioral Signs Associated With Equine Periapical Infection in Cheek Teeth.

Journal of Equine Veterinary Science. 2019;77:144-150.

2 Zoetis Equine Dental Risk-Assessment Survey Results. Zoetis U.S. Market Research. May 30, 2020 3 Data on file, 2020 Equine Pain & Sedation Market Research Study. Aug. 10, 2020 All trademarks are the property of Zoetis Services LLC or a related company or a licensor unless otherwise noted.

DORMOSEDAN is trademark owned by Orion Corporation Orion Pharma Animal Health. It is manufactured by Orion Corporation and distributed by Zoetis under license from Orion Corporation Orion Pharma Animal Health. © 2021 Zoetis Services LLC. All rights reserved. GEQ-00676

ModernEquineVet.com | Issue 3/2021

9

CARDIOLOGY

Patch ECG Compares Well to Conventional Monitor for Long-Term Cardiac Tests

Photos courtesy of Dr. John A. Keen

By Adam Marcus A novel system of disposable electrocardiography (ECG) patches provides reliable information about equine arrhythmias for as long as a week, a recent study shows.

Researchers in the United Kingdom tested the Carnation Ambulatory Monitor on 21 horses to determine optimal positioning of the device and to assess its performance relative to telemetric electrocardiography. The array appeared to work best when located along the ventral midline caudal to the xiphisternum.

Once placed, the patches generated high-quality signals for up to 7 days, according to the researchers. However, the disposable patches performed best while the animals were at rest, providing generally unreliable results during periods of exercise.

The patch in place on the horse.

The researchers, who published their findings in a recent issue of the Journal of Veterinary Cardiology, said the new system is easier to use than conventional ECGs, such as the Holter monitor.

“The benefit of these over the traditional wirebased monitors is their convenience and disposable nature, meaning a clinic can send these out without worrying about their expensive monitors being rolled on and broken,” said John A. Keen, BVetMed, PhD, of the Department of Veterinary Clinical Studies at the The Royal (Dick) School of Veterinary Studies and the Roslin Institute, at the University of Edinburgh, in Midlothian, who led the study. “Also, because there are no long wires dangling around, it’s more convenient to have these on for a few days and you can easily ride the horse.”

What’s more, Dr. Keen said, clinics are reluctant to send out telemetric monitors for extended periods, because the devices are expensive and, in some cases, may be their only ECG equipment.

Since publishing the paper, Dr. Keen said he has performed another 15 to 20 exams. “These are clinical cases where there is episodic/intermittent collapse—either suspected or actually observed—that may be associated with an arrhythmia or cases where there is a perceived increased risk of arrhythmia, or where there is an arrhythmia that I feel warrants longer-term monitoring to fully characterize the frequency of the arrhythmia.”

Dr. Keen described the quality of the studies as “generally very good at rest, and these examinations have invariably been useful diagnostically,” but added that they are not a replacement for standard ECGs during exercise testing.

“The significant artefact associated with exercise drowns out the quality of the ECG signal. Even with a standard ECG the exercising trace can be a problem and one of the 'holy grails' for us equine cardiologists is artefact-free ECG traces at exercise—often a problem in anything other than racehorses! I’d like to play around with patch positioning some more to see if I can get these devices any better for exercise ECGs but my suspicion is it won’t get that much better with the current technology.”

MeV

For more information: Keen JA et al. Evaluation of a novel ambulatory electrocardiogram monitor (the Carnation Ambulatory Monitor) for use in horses. J Vet Cardiol. 2021;34:16-28. https://doi.org/10.1016/j.jvc.2020.12.005 10

Issue 3/2021 | ModernEquineVet.com

INFECTIOUS DISEASES

2 L of REHIP More Effective Than 1 L, Study Shows

By Adam Marcus Transfusing 2 L of plasma hyperimmune against R. equi (REHIP) simultaneously is significantly better than administering 1 L of the substance for the prevention of pneumonia in foals, reducing the incidence by more than 50%, even when accounting for variability in the time of year the animals were born, according to Patricia FloresAhlschwede, DVM. Rhodococcus equi is a major source of pneumonia in newborn foals but can be controlled by transfusions of REHIP. However, the optimal volume of plasma to administer, and in what timeframe, has been unclear. This study should help clarify the question, she said during a presentation at the 2020 virtual meeting of the American Association for Equine Practitioners.

Led by Dr. Flores-Ahlschwede, of the Rood and Riddle Equine Hospital in Saratoga, N.Y., the researchers reviewed the records of 158 foals born on 2 farms in New York. Animals were considered to have R. equi pneumonia if they had lung abscesses of 1 cm or larger, and 3 or more of the following clinical signs: • coughing, • abnormally rapid breathing, • labored breathing, • fever or • lethargy.

Of the 64 foals that received 2 L of REHIP, 19 (30%) developed clinical pneumonia, compared with 58 of the 94 (62%) that received 1 L of the therapy (P=0.05),

according to the researchers.

Animals born in the spring (April or May) were more likely to develop pneumonia than those born before April (59% vs. 39%; P=0.01769). However, even after adjusting for the month of birth, the advantage of 2 L of REHIP remained statistically significant (P=0.0457), the researchers reported.

“Based on the evidence we have to date, I would recommend transfusing 2 L of REHIP to foals at farms where the disease is prevalent on a recurring basis in order to reduce the cumulative incidence of R. equi pneumonia,” said study co-author Noah D. Cohen, VMD, MPH, PhD, DACVIM-LA, the Patsy Link Chair in Equine Research, and the director of the Equine Infectious Disease Laboratory at the Texas A & M University College of Veterinary Medicine & Biomedical Sciences, in College Station.

Although some veterinarians may already be transfusing 2 L, Dr. Cohen said he suspects the majority do not. “I do not think most vets transfuse 2 L simultaneously, but it is my belief and hope that the practice is increasing because I think it protects foals,” he told Modern Equine Vet. Cohen noted that the new study has a few limitations, including that it was observational. “It would be better if we had a randomized, controlled trial to demonstrate unequivocally for veterinarians and horse owners that transfusion of 2 L is superior to 1 L to control this difficult disease.”

MeV

Shutterstock/Buffy1982

Foals born in April or May were more likely to develop pneumonia than those born earlier.

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Issue 3/2021 | ModernEquineVet.com

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LAMINITIS

An EvidenceBased Look at

Multimodal Laminitis Treatments B

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It would be a bit of an understatement to say that pain manage-

ment in the laminitic horse is challenging. Between the types of pain and the dearth of evidence on the multitude of treatment options, clinicians often find themselves in the weeds.

In addition to therapeutic shoeing and hoof support, multimodal treatment typically gives a patient their best shot at recovery. But which ones to try? And what about the evidence?

To help firm up the veterinarian’s armamentarium, Katherine Ellis, DVM, a clinician in equine sports medicine rehabilitation at the University of Georgia, recently described several pharmaceutical and non-pharmaceutical modalities in a virtual presentation at the 66th AAEP Annual Convention.

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Shutterstock/Gus Photoaddict

CASE #1: Too Much of a Good Thing

Dr. Ellis described a 14-year-old Quarter Horse gelding that managed to make his way into the feed room and ate half of a bag of sweet feed within 24 hours. The horse had an acute AAEP grade 4 lameness in both forelimbs and moderately increased digital pulses.

“For this horse, you might consider an NSAID, digital hypothermia and vasodilators, such as pentoxifylline and acepromazine, which do not have direct analgesic effects,” she said.

Anecdotally, many clinicians regard phenylbutazone as the most efficacious and consistent nonsteroidal anti-inflammatory (NSAID), but several studies offer alternatives. “Although they may not have evaluated laminitic horses, other studies have shown that other NSAIDs may be as effective as

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LAMINITIS

phenylbutazone,” Dr. Ellis said.

Doucet, et al, for example, showed that firocoxib at 0.1 mg/kg every 24 hours was as effective as phenylbutazone at 4.4 mg/kg orally every 24 hours for horses with osteoarthritis. A 2005 study looking at navicular syndrome showed that flunixin meglumine 1.1 mg/kg IV was as effective as phenylbutazone 4.4 mg/kg orally.

“If laminitic pain is not controlled with one NSAID, it might be worthwhile to try a different one,” she added, “although evidence in the laminitic horse is lacking.”

A 1995 study involving horses with naturally occurring, bilateral laminitis showed that ketoprofen at 3.63 mg/kg was more effective at controlling pain than phenylbutazone at 4.4 mg/kg.

One modality that does have the backing of a breadth-of-controlled research studies is icing. Continuous digital hypothermia performed just below the carpus using an ice boot or an ice bath can significantly reduce lamellar injury.

Vasodilators such as pentoxifylline have no direct analgesic effects, but they are thought to have indirect effects by helping to restore normal blood flow to the foot. But is there evidence for use in equine laminitis?

“Unfortunately not,” Dr. Ellis said.

Some things are known, such as pentoxifylline’s extremely variable absorption in the horse after oral administration. Another study found that pentoxifylline at 4.4 mg/kg orally every 8 hours for 10 days did not increase blood flow in the digit of healthy horses. It has also not been evaluated in the laminitic horse.

Another drug that has no direct analgesic effect is acepromazine, a phenothiazine tranquilizer.

“We do have studies that show increased blood flow and arterial diameter in the dorsal metatarsal artery in horses,” she explained. “In addition, IV administration at 0.06 mg/kg has been shown to increase digital and

DO BIOLOGICS HELP? Biologic therapies, such as stem cells and platelet-rich protein (PRP), have been used in laminitic horses, predominantly for their anti-inflammatory effects.

As far as evidence goes, one study looked at return-to-use in 9 horses with chronic laminitis. Horses received 3 to 6 regional limb perfusions with adipose-derived stem cells at monthly intervals, and all horses were back to use 6 months after treatment.

In another study, 15 horses were treated with either IV regional limb perfusion or intra-arterial stem cells.

“The intra-arterial stem cells were shown to have a better distribution in the foot than with the IVRP,” Dr. Kate Ellis said.

“However, no significant difference in success by treatment route was appreciated.”

FOR MORE INFORMATION: Angelone M, et al. The contribution of adipose-tissue-derived mesenchymal stem cells and platelet-rich plasma to the treatment of chronic equine laminitis: a proof of concept. Int J Mol Sci 2017;18:1-17. laminar blood flow in normal horses.”

These studies have shown an increase in digital blood flow in healthy horses, but it is unknown if the increase occurs in laminitic horses as well.

CASE #2: Chronic Laminitis in the Field

A 25-year-old Paint gelding with a prior history of pituitary pars intermedia dysfunction (PPID) has chronic laminitis, predominantly affecting the front feet. Previous episodes have typically improved after a few days of phenylbutazone, but the current episode has lasted for 2

For more information: Owens JG, et al. Effects of ketoprofen and phenylbutazone on chronic hoof pain and lameness in the horse. Equine Vet J 1995;27:296-300.

Doucet MY, 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;232:91-97.

Erker RS, et al. Use of force plate analysis to compare the analgesic effects of intravenous administration of phenylbutazone and flunixin meglumine in horses with navicular syndrome. Am J Vet Res 2005;66:284-288.

Liska DA, et al. Pharmacokinetics of pentoxifylline and its 5-hydroxyhexyl metabolite after oral and intravenous administration of pentoxifylline to healthy adult horses. Am J Vet Res 2006;67:1621-1627.

Ingle-Fehr JE and Baxter GM. The effect of oral isoxsuprine and pentoxifylline on digital laminar blood flow in healthy horses. Vet Surg 1999;28:154-160.

Hunt RJ, et al. Effects of acetylpromazine, xylazine, and vertical load on digital arterial blood flow in horses. Am J Vet Res 1994;55:375-378.

Caldwell FJ, et al. Effect of PO administered gabapentin on chronic lameness in horses. J Equine Vet Sci 2015;35:536-540.

Faramarzi B, et al. Response to acupuncture treatment in horses with chronic laminitis. Can Vet J 58(8):823-827.

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Photos courtesy of Dr. Katherine Ellis

A pony with chronic laminitis.

weeks with no improvement. His appetite has also been decreased, and central sensitization is suspected.

“You might consider continuing to use an NSAID given the horse’s pain level, but I would consider switching to firocoxib, given the decreased appetite and chronic use of phenylbutazone,” Dr. Ellis said. “Since we have evidence of central sensitization, we could also try gabapentin and some non-traditional treatments, such as transcutaneous electrical nerve stimulation [TENS], acupuncture, and manual therapy.”

Gabapentin has shown mixed results in horses. One

study evaluated gabapentin at either 5 mg/kg or 10 mg/ kg orally 3 times daily for 14 days in horses with chronic osteoarthritis. No significant improvement in lameness was seen with either dose.

“There have been some individual case reports in horses with chronic laminitis that showed improvement with gabapentin.” Dr. Ellis added. “It has a low bioavailability when administered orally, so higher doses are likely needed to be effective.”

Unfortunately, there is no evidence in horses— laminitis or not—regarding TENS therapy. “All of our evidence comes from human medicine, which does show some conflicting results,” she explained. “However, many studies have shown improved pain control for both postoperative pain and chronic pain.”

Acupuncture, however, has been studied more in horses. One study showed that 2 acupuncture treatments performed 1 week apart improved lameness scores in horses with chronic laminitis. Another study showed improvements in subjective pain levels in 6 of 7 horses with chronic laminitis.

For secondary pain of the axial skeleton, manual therapy, such as massage, chiropractic and physiotherapies, can also be considered.

“While evidence for pharmaceutical and non-pharmaceutical approaches in the laminate course are somewhat limited,” Dr. Ellis concluded, “We do have multiple treatment options available.”

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OA of Caudal Cervical Region Common in Warmbloods Osteoarthritis (OA) of the caudal cervical region is a relatively common finding in radiographs of actively performing Warmblood jumpers, which suggests this finding may be of less clinical significance than previously thought, according to a recent study.

Researchers performed a descriptive study aimed to assess the prevalence of cervical OA in a group of Warmblood jumpers to ascertain its correlation with age, level of performance, neck pain and mobility. During a competition series in California, they enrolled 108 sound Warmblood show jumpers that had competed in at least 10 classes. The median age of the population was 10 years and the median height of the current level of performance was 1.3 m

Cervical pain and range of motion of the neck were subjectively assessed. Lateral radiographs of the cervical spine were taken from C3 to C7 and the presence of OA at the cervical articular process joints (APJs) was evaluated and graded as absent, mild or moderate to severe by 3 board-certified radiologists.

The prevalence of OA increased caudally, with the C6–C7 APJ most commonly affected by OA (63% of horses). Horses competing in higher level classes had significantly higher OA grades at C6–C7. This correlation was not significant for the remaining APJ. There was no association between age, time jumping, neck pain and neck range of motion with the presence of OA on radiographs.

For more information: Esoinosa-Mur P, Phillips KL, Galuppo LD. Radiological prevalence of osteoarthritis of the cervical region in 104 performing Warmblood jumpers.

Equine Vet J. 2020 Nov. 10 https://doi.org/10.1111/evj.13383 https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13383 ModernEquineVet.com | Issue 3/2021

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