The Modern Equine Vet - September 2019

The Modern

Equine Vet www.modernequinevet.com

Vol 9 Issue 9 2019

Endocrine Disease

More Horses at Risk Today Ask the Nutritionist? Polysaccaride Storage Myopathy Rotary Burs Can Get Tough Teeth Moving 24 Ways Horses Communicate Pain

NEW FEATURE: ASK THE NUTRITIONIST? YOUR NUTRITION QUESTIONS ANSWERED

TABLE OF CONTENTS

COVER STORY

4 Endocrine Disease Rates Increase; More Horses at Risk Cover photo: Shutterstock/Groomee

ASK THE NUTRITIONIST?

Nutritional Management for Horses with PSSM1 vs. PSSM2?.......................................................................................... 3 DENTISTRY

NEWS

Morphological Variations in the Caudal Cervical Spine...........................11

Rotary Burs Can Get Tough Teeth Moving ............................................ 8 BEHAVIOR

24 Ways Your Patients Tell You They’re in Pain.......................................12 NUTRITION

Effects of Nitrate on Reproductive Losses and Newborn Congenital Issues........................................................................17 COLIC

Colic Puts a Thoroughbred Down, But Not Out.....................................19

ADVERTISERS Purina Sponsored Content............................................................ 3 Standlee Premium Western Forage............................................ 5 AVMA | PLIT....................................................................................... 7 American Regent Animal Health/Adequan.............................. 9

Stokes Healthcare......................................................................... 11 Heska............................................................................................... 13 American Regent Animal Health/BetaVet.............................. 15

The Modern

Equine Vet SALES: Matthew Todd • Lillie Collett 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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LEGAL DISCLAIMER: The content in this digital issue is for general informational purposes only. PercyBo Publishing Media LLC makes no representations or warranties of any kind about the completeness, accuracy, timeliness, reliability or suitability of any of the information, including content or advertisements, contained in any of its digital content and expressly disclaims liability of any errors or omissions that may be presented within its content. PercyBo Publishing Media LLC reserves the right to alter or correct any content without any obligations. Furthermore, PercyBo disclaims any and all liability for any direct, indirect, or other damages arising from the use or misuse of the information presented in its digital content. The views expressed in its digital content are those of sources and authors and do not necessarily reflect the opinion or policy of PercyBo. The content is for veterinary professionals. ALL RIGHTS RESERVED. Reproduction in whole or in part without permission is prohibited.

SPECIAL ADVERTISING SECTION

Ask the

?

Nutritionist

DR. KAREN DAVISON, PH.D., DIRECTOR OF EQUINE TECHNICAL SOLUTIONS, PURINA ANIMAL NUTRITION

Ask the Nutritionist is a new monthly column featuring questions answered

by PhD equine nutritionists and sponsored by Purina Animal Nutrition.

Have a nutrition question you want to see featured? Email the Editor. For clinics looking for specific nutritional advice, visit purinamills.com/ask-an-expert.

What is the difference between nutritionally managing horses with PSSM1 (Type 1 Polysaccharide Storage Myopathy) vs. PSSM2 (Type 2 Polysaccharide Storage Myopathy)?

PSSM1 and PSSM2 are different disorders with slightly different recommendations for nutritional management.

Horses with PSSM1 are more sensitive to dietary starch and sugar levels, because they accumulate more muscle glycogen than normal horses or horses with PSSM2. PSSM1 horses also benefit from more calories supplied by dietary fat because they possess the GYS1 mutation and store an amylaseresistant polysaccharide, which can’t be used as substrate for working muscle fibers. Training adaptation and a diet consisting of higher dietary fat can shift certain muscle fibers to rely more on fatty acids, and less on glycogen, to fuel exercise.

Diets for horses with PSSM1 should be low in starch and sugar (nonstructural carbohydrates – NSC) and supply more calories from vegetable oils. “Easy keepers” or less active PSSM1 horses may not be able to consume higher fat levels without becoming overweight. In these cases, use forages low in starch and sugar (<12% NSC) and a ration balancer, like Purina® Enrich Plus® horse feed, to meet nutrient requirements. Specific dietary NSC and fat levels that best mange each case will vary by horse and total calorie demand.

Horses with PSSM2 have abnormal muscle histology with glycogen aggregation, but do not possess the GYS1 mutation, accumulate excess glycogen or store an abnormal polysaccharide. Dietary recommendations for

PSSM2 are not as well defined, but PSSM2 horses don’t seem to be as sensitive to dietary starch and sugar levels as PSSM1 horses.

Current recommendations for PSSM2 cases call for the use of low- to moderate-NSC feeds and fat supplementation based on the horse’s energy needs. Research suggests that amino acid supplementation, using whey protein-based supplements like Purina® SuperSport® Amino Acid Supplement, can be helpful in optimizing muscle recovery following exercise.1 These supplements may also be helpful when managing symptoms in horses with PSSM2. 2 There is no one-size-fits-all diet for horses with PSSM1 or PSSM2. Finding the levels of soluble carbohydrates, fat and other supportive nutrients such as amino acids that best manage PSSM symptoms for an individual horse may require some trial and error. It’s important to note regular exercise is at least as important as diet in managing horses with PSSM1 or PSSM2.

1.Vineyard, K.R., M.E. Gordon, P. Graham-Thiers, and M. Jerina. 2013. Effects of daily administration of an amino acid-based supplement on muscle and exercise metabolism in working horses. Journal of Equine Veterinary Science, Vol 33(5).

2.Williams ZJ, Bertels M, Valberg SJ. 2018. Muscle glycogen concentrations and response to diet and exercise regimes in Warmblood horses with type 2 Polysaccharide Storage Myopathy. PLoS ONE 13(9): e0203467.

ABOUT THE AUTHOR Dr. Karen Davison is the Director of Equine Technical Solutions at Purina Animal Nutrition. She earned her Master of Science and Ph.D. degrees in Equine Nutrition from Texas A&M University. Dr. Davison's research has included the use of added fat in horse diets and the effects of higher fat diets on reproduction and lactation in broodmares and on development of weanling horses. Dr. Davison has guest-lectured at universities and veterinary schools, contributed to scientific research journals and magazines, authored book chapters and presented at regional and national veterinary meetings.

SPONSORED BY PURINA ANIMAL NUTRITION

ModernEquineVet.com | Issue 9/2019

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ENDOCRINE

Endocrine Disease Rates Increase More Horses at Risk

As horses are living longer, endocrine diseases are becoming more com-

mon, but to diagnose them requires looking at the entire picture, not just a test result, according to two experts.

“You're going to be seeing a lot of these things in clinical practice,” said Elizabeth M. Tadros, DVM, PhD, DACVIM, assistant professor of endocrinology at Michigan State University College of Veterinary Medicine. “It's important to screen for endocrine diseases as part of routine wellness examinations.”

The most common endocrine disorders are insulin dysregulation (ID), equine metabolic syndrome (EMS) and pituitary pars intermedia dysfunction (PPID).

Although PPID is common in older horses, it is rare in horses younger than 10. “So, testing in those cases is generally not recommended,” Dr. Tadros said. “It tends to be a disease of horses that are perhaps 15 years of age and older. But the important point is that laminitis can occur in up to half of those animals that have PPID. So it is something that you do want to identify as far as its pathogenesis.”

Diane McFarlane, DVM, PhD, DACVIM, agreed.

“Age is an important factor in reaching this diagnosis. And to put a little bit of data behind that statement: There are 4 prospective studies of pathology that looked at over 450 pituitary glands, and in these 450 pituitary glands, there were no horses under 10 years of age that had pathology or grading supportive of PPID,” she said.

“This is an aged-horse disease,” said Dr. McFarlane, professor in the Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University.

Many horses, but not all, have hypertrichosis, according to Dr. Tadros. “However it is by no means certain that all horses with

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M a r i e

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ENDOCRIN0LOGY

PPID especially in the early stages of the disease have hypertrichosis, so you do have animals that just have muscle wasting or perhaps they're presenting with chronic infections or dental disease or sinusitis,” long before they have the hair coat problems. Regional adiposity is also common.

Adrenocorticotropic hormone (ACTH) is overproduced in these animals, so that is one of the best biomarkers for PPID.

EMS

Younger adults tend to have EMS, which has a triad of signs: insulin

dysregulation, obesity and often regional adiposity and laminitis.

“Now, this tends to be a disease of younger animals,” Dr. Tadros said, although it can appear in older horses, too. “So, we don't want to forget about this in our geriatrics either,” she added.

“These thrifty animals are ones that are able to efficiently process nutrients, and that probably gave them a survival advantage,” Dr. Tadros explained. “However, in today's world where there certainly is an abundance of food, those traits that used to be adaptive helping an animal get through a hard winter—be-

TEST

FOR

TYPE NOTES OF TEST

Resting insulin concentration

ID

Static

Oral glucose challenge

ID

Dynamic Fast the horse for 3-8 hrs. Take baseline blood insulin and glucose measurements. Administer corn syrup using a dosing syringe. Collect additional serum samples at 60 and 90 minutes. Insulin response >45 µU/mL indicates ID.

In-Feed Oral Glucose Test

ID

Dynamic Fast the animal overnight. Collect baseline blood insulin and glucose.

Administer dextrose powder in a non glycemic feed. Collect blood at 2 hrs.

Insulin response >68 µU/mL for 0.5 g/kg or >85 µU/mL for 1 g/kg indicates ID.

Insulin Tolerance Test

ID

Dynamic Do not fast horse before testing. Collect blood glucose sample. Administer 0.10 IU/kg IV soluble insulin. Take blood sample 30 min later. If glucose does not drop to 50% or more of the baseline value, indicates insulin resistance. Test carries a small risk of hypoglycemia.

Combined Glucose Insulin Tolerance Test

ID

Dynamic Collect baseline blood insulin and glucose samples, followed by concurrent administration of 150 mg/kg dextrose + 0.1 U/kg IV soluble insulin. Failing to return to baseline glucose concentration or an insulin concentration >100 µU/mL indicative of insulin resistance. Small risk of hypoglycemia

Resting Endogenous plasma adrenocorticotropic hormone (ACTH)

PPID

Static

Collect samples after eating. Perform tests at least 4 hours after a concentrate meal. Hyperinsulinemia is suggestive of ID.

No need to fast horse. Collect samples any time of day. Use appropriate seasonal reference ranges, because ACTH concentrations increase from mid-July to –November. False positives can occur

Thyrotropin PPID releasing hormone (TRH) stimulation tests

Dynamic Collect baseline plasma ACTH sample, then administer IV TRH. Take a second plasma sample 10 minutes later. At that time, plasma ACTH concentrations >200 pg/mL indicative of PPID. There are no established fall seasonal reference ranges. Do not perform test between mid-July and –November.

Overnight PPID Dexamethasone Suppression Test

Dynamic Take a baseline cortisol sample in the late afternoon of day 1. Administer dexamethasone. Take a second blood cortisol sample 15-19 hrs. later. If cortisol concentration does not suppress to <30 nmol/L, indicative of PPID. Test takes 2 days to perform. Fall reference ranges have not been established.

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ing able to store a lot of fat—having some of these metabolic features is no longer adaptive today.”

Instead, the animals become obese, which has profound effects on insulin dynamics. “These animals that start off with insulin dysregulation and metabolic syndrome can then progress on to develop conditions, such as PPID in later in life,” she explained.

Insulin Dysregulation

Age is not necessarily a factor for ID, a metabolic derangement, which is central to the pathogenesis of EMS, according to Dr. Tadros, and can affect up to 60% of horses with PPID. Signs include fasting hyperinsulinemia, postprandial hyperinsulinemia, exaggerated responses to carbohydrates, insulin resistance and dyslipidemia.

If not properly managed, conditions like PPID, EMS and ID can lead to laminitis because high circulating insulin over activates the laminar epidermal epithelial cell insulin-like growth factor-1 receptor, causing abnormal tissue growth and weakening the laminar.

These conditions often overlap, so a veterinarian can see a horse with obesity, ID and PPID; a horse that is not necessarily obese with ID and PPID, and horses that are obese, have EMS and ID, she explained.

Diagnostic Testing

“Although endocrine disease is quite common to see in practice, and we do know a lot about it, it still seems to be fairly difficult to reach the diagnosis,” Dr. McFarlane said. “And there are several reasons for this.

First of all, the diseases are insidious, and so the clinical signs kind of creep up on you.”

Second, the onset of clinical signs associated with these conditions have been poorly described, and there is an overlap of clinical signs with general aging, she said.

And in geriatric horses, there are plenty of differentials that could explain an issue like weight loss, Dr. Tadros reminded.

Look at the horse holistically, suggested Dr. McFarlane. A holistic approach would include the history signalment, clinical signs and whether there's progression of those signs, as well as diagnostic tests.

“Typically, when you do blood analysis, you may have some evidence of other concurrent geriatric issues, but a lot of times their CBCs and biochemistry are normal. In my experience, sometimes these animals will have an abnormal lipid profile and hyper triglycerides, and sometimes elevated liver enzymes,” Dr. Tadros said.

Some veterinarians also do thyroid testing, and it is common to see slightly lower thyroid hormone

concentrations, according to Dr. Tadros. “To me, this should be a tip off to test for other metabolic issues. These horses almost uniformly have your thyroid sick syndrome, they are not hyperthyroid, but if you do see slightly low T for values, that should be an indication to go look for something else.”

While static tests—measuring a blood sample at a single point—is fast and inexpensive, they don’t have very good sensitivity, so they can miss early PPID. Dynamic tests are better because they “rattle the system a bit” and you can watch how the body compensates, which is more likely to unmask abnormalities, according to Dr. Tadros.

“Endocrine systems are a bit tricky,” Dr. Tadros said. “They're like moving targets. So, if there's

a discrepancy between the clinical case versus the test results, I always tend to believe the clinical case.”

In those cases, it would not be wrong to retest.

Horses can have more than one endocrine condition, which would make interpreting the results even more difficult, they said.

Remember, when measuring ACTH, the specificity of that test is only 80%. That means it is falsepositive 20% of the time—20% of the patients that test positive with an ACTH do not have PPID. “We cannot say an animal has PPID just because its ACTH is high, we need to have a more holistic approach and know that they also have some clinical signs, or we have ignored the 20% of the time, it's a false positive,” Dr. MacFarlane said.

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DENTISTRY

Rotary Burs

Can Get Tough Teeth Moving

Shuttersotck/Anastasija Popova

B y Some teeth just don’t want to let go, and more equine dentists are turning to rotary burs to facilitate extractions in difficult cases.

Burs require a bit of a learning curve and a significant cost outlay at the start, but with a little practice and a steady hand, this method can provide a viable alternative to more invasive procedures,

such as tooth repulsion and lateral buccotomy, according to Molly K. Rice, DVM, DAVDC-EQ, of the Midwest Veterinary Dental Services in Elkhorn, Wis.

Partial coronectomy

If traditional extraction techniques—sulcular incision, gingival elevation, molar spreading and use of extended luxators—

P a u l

B a s i l i o

appear to run an unacceptable risk of fracture or crumbling of the clinical crown, partial coronectomy can be performed.

“This technique is designed for teeth that aren’t going to fare well with traditional extraction methods,” Dr. Rice said. “If you were to place spreaders on [diseased cheek teeth], the chances of fracturing the remaining clinical

Equipment Several instruments may be modified for bur work, but Dr. Molly K. Rice’s practice uses the Versa-Float, which allows for water irrigation during the procedure.

“It’s important to have water irrigation when you’re making these cuts,” she said. “It prevents thermal damage to the neighboring tooth and the alveolar bone.”

For the burs, a trip to the hardware store for an inexpensive tile cutting bur is in order, although there are a variety of 8

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exntended length burs that are sold specifically for equine teeth. A variety of lengths are necessary, particularly when attempting to section a tooth.

“You need a variety of lengths because you have to have a bur long enough to reach that root furcation, when the burs are used for tooth sectioning,” she said. “Depending on the age of the horse, sometimes you can have a fairly deep cut.”

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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.

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DENTISTRY

Step by Step • Ensure proper cut alignment through frequent use of intraoperative radiographs. Failure to identify a proper alignment may contribute to crown failure due to excessive tooth removal.

• Remove the clinical crown to the level of the crestal bone.

Visualize that a complete cut has been made on a radiograph.

• Typically, starting with a distal interproximal cut is preferred, as this can facilitate spreading and delivery of the tooth along the pathway of eruption. In a tooth with a complicated fracture through pulp horns 3 and 5, for example, a mesial interproximal cut may make more sense, as there is a missing portion of crown there already.

• After the completed cut has been confirmed on radiography, molar spreaders or extended luxators may be applied to facilitate loosening in a mesial to distal direction.

• If the tooth does not loosen, examine the radiographs to determine whether the cut can be extended deeper. A cut on the other interproximal border may be made to facilitate further loosening as well.

"If you are going to place spreaders on [diseased cheek teeth], the chances of fracturing the remaining clinical crown is fairly high. You are going to be stuck with nothing ... to put your forceps on."

Molly K. Rice, DVM, DAVDC-EQ crown is fairly high. You’re going to be stuck with nothing left in the mouth to put your forceps on.”

The idea behind a partial coronectomy is to remove part of the tooth and reserve crown at the interproximal space to the level of the crestal bone. This effectively removes the crown interlock that’s present in a normal dental quadrant.

Getting a Grasp on It

“That’s one of the challenges we face when we extract cheek teeth,” Dr. Rice said. “By reducing that crown interlock, we’re able to get that tooth moving by putting less force on it.”

Some of the easiest teeth to extract are those surrounded by periodontal disease, thanks to the attachment loss. If a diastema is present, it allows a space for standard instruments to grab hold and allow rostrocaudal motion.

“This technique builds on that,” she added. “We’re trying to create a

space so we can get that tooth moving without having to put a lot of force on a potentially diseased or fractured crown.”

Creating a 3-mm space can significantly decrease surgery time in many cases. “When you get the cut completed in the interproximal space up to the level of the crestal bone—the bone in between the theeth—you can induce significant mobility in these teeth often within 10 to 15 minutes,” she said.

Although effective, the process may take some time to implement.

“If you’re starting to think about trying this method, practice on cadavers before trying it on a live patient,” she said.

“There are a lot of ways you can get yourself in trouble pretty quickly.”

MeV Dr. Rise spoke at the 64th Annual AAEP Convention in San Francisco.

WATCH WHERE YOU’RE GOING ON MANDIBULAR TEETH, THE PROCESS MUST BE GUIDED BY RADIOGRAPHY.

“Even though our practice has all of the fancy digital radiography machines, we still use intraoral computed radiographs when guiding the this process in mandibular teeth because we need a clear image of these teeth,” Dr. Molly K. Rice said. “We can see the progression of the cuts as we go along.”

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NEWS NOTES

Morphological Variations in the Caudal Cervical Spine Radiographic morphologic variations in the caudal cervical spine are more common in horses without relevant clinical signs, and so should be interpreted with care, researchers warned.

This case-control study investigated the clinical relevance of radiographically visible morphologic variations in the caudal cervical vertebrae of Warmbloods.

Cervical radiographic examinations of all Warmblood horses (with and without clinical signs) performed between January 2011 and December 2013 were reviewed by a board-certified radiologist.

Morphologic variations recorded included absence of a ventral laminar part of the transverse process in combination with a ventral protuberance at another transverse process and the presence or absence of degenerative joint disease of the articular facet joint of C6 and C7. Clinical signs considered relevant included spinal ataxia, restricted flexion of the neck, cervical pain on palpation, abnormal behavior (e.g. head shaking, bolting), cervical muscle

atrophy, presumed thoracic neurological lameness and hypermetric gait. Univariable Pearson’s Chisquare and multivariable logistic regression were used to compare the cases and controls.

In total, 245 cases and 132 controls were included in the study. Morphologic variation at C6 and C7 was significantly less frequent in horses with clinical signs (23.7%) compared with the control group (38%). Age, sex, breed and degenerative joint disease were not associated with the presence of clinical signs.

MeV

For more information: Veraa S, de Graaf K, Wijnberg ID, et al. Caudal cervical vertebral morphological variation is not associated with clinical signs in Warmblood horses. Equine Vet J. 2019 June 18. (Epub ahead of print). https://onlinelibrary.wiley.com/doi/10.1111/evj.13140

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BEHAVIOR

24YourWAYS Patients Tell You They’re in Pain It’s becoming clearer that

horses are particularly skilled at communicating when they are in pain—the communication problem appears to be on our end.

Building off previous research that showed even lay observers could reliably recognize a painful horse by focusing on specific facial expressions, Sue Dyson, Vet MB, PhD, DECVSMR, FRCVS, and colleagues applied the idea to the whole horse.

Using a whole-horse ridden ethogram—a catalogue of behaviors with descriptions—the investigators were able to show a causal relationship between pain and a specific group of behaviors.

“I believe that by the behavior which the horses exhibit, they are trying to communicate with us,” Dr. Dyson said. “We need to learn

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to listen. Behavioral signs exhibited during ridden exercise may be a manifestation of musculoskeletal pain.”

In a previous study of 506 sport horses presumed to be sound, 47% exhibited either lameness or other pain-related gait abnormalities.

Problems during exercise were often written off as training-related, rider-related, behavioral, or by saying, ‘that’s just how the horse is.’

“I believe that our profession has had a lack of training for recognition of low-grade lameness, and a lack of training for the identification of behavioral abnormalities,” Dr. Dyson said.

The study

Twenty-one lame horses were videotaped before and after diagnostic anesthesia. The horses were

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Imaging the Possibilities

BEHAVIOR

The Ethogram FACIAL MARKERS 1 Ears rotated back behind vertical or flat for more than 5 seconds 2 Eyelids closed or half-closed for 2-5 seconds 3 Sclera exposed 4 Intense stare for 5 seconds 5 Mouth opening ± shutting repeatedly with separation of teeth for more than 10 seconds 6 Tongue exposed, protruding or hanging out, and/or moving in and out 7 Bit pulled through the mouth on the left or right.

BODY MARKERS 8 Repeated changes of head position (up/down) 9 Head tilted or tilting repeatedly 10 Head in front of vertical (>30°) for more than 10 seconds 11 Head behind vertical for more than 10 seconds 12 Head position changed regularly, tossed or twisted from side to side, corrected constantly

ridden by a professional rider, and the footage showed both working trots and working canter on the left and the right reins.

Lameness scores in the study horses ranged from 1-4/8; the most common lameness grade was 2/8.

The assessors consisted of 10 untrained individuals and 1 trained professional—the “gold standard” assessor. They were told that they were viewing 42 recordings of both lame and non-lame horses instead of before-and-after videos of the 21 horses.

The assessors independently tracked the number of behaviors that were exhibited during a given video, and each horse was scored appropriately. Previous research had determined that the presence of 8 or more of these behavioral markers was likely to reflect musculoskeletal pain.

“We hypothesized that there 14

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13 Tail clamped tightly to middle or held to one side 14 Large tail swishing movements GAIT MARKERS 15 Rushed gait (>40 trot steps per 15 seconds), irregular rhythm in trot or canter, or repeated changes in speed in trot or canter 16 Gait too slow (<35 trot steps per 15 seconds) 17 Hindlimbs do not follow tracks of forelimbs 18 Canter: having repeated strike-offs on wrong leg, or change of leg in front and/or behind (disunited) 19 Spontaneous changes of gait (eg, breaks from canter to trot or trot to canter) 20 Stumbles or trips repeatedly; repeated toe drag 21 Sudden change of direction against rider direction 22 Reluctance to move forward 23 Rearing 24 Bucking or kicking backward

would be significant reduction in behavior scores after resolution of pain by diagnostic analgesia determined by both the gold standard assessor and by the untrained assessors,” Dr. Dyson said.

Results from the gold standard assessor showed that lame horses had scores ranging from 3-12/24 (median 10; mean 8.9) prior to diagnostic analgesia, and 0-6/24 (median 3; mean 3.0) following the block. The difference in behavior scores before and after analgesia ranged from 2 to 12/24 (median 6; mean 6).

There was a highly significant decrease in behavior scores after abolition of lameness for all assessors.

“The reduction in the behavior scores after pain resolution verifies a likely causal relationship between pain and these behaviors,” Dr. Dyson said. “This study provides further evidence that the

presence of 8 or more behavioral markers is likely to reflect musculoskeletal pain. However, we did see overlap between the non-lame and the lame horses. Four horses in the current study—when assessed by the expert—had total behavior scores of 3, 4, 6 and 7, respectively.”

Training the assessors has also shown to improve the repeatability of the ethogram’s application.

“Training is required for correct application and interpretation of the ethogram,” Dr. Dyson explained. “Even if a horse appears non-lame in hand, it may be lame when ridden. This may be manifest by its behavior, which is an indicator that something is not right.

“The horse is trying to communicate with us,” she added.

“We must listen to it.”

MeV Dr. Dyson spoke at the 64th Annual AAEP Convention in San Francisco.

The only dual ingredient injectable corticosteroid approved by the FDA for use in horses

The link between RAPID ONSET and LONG-ACTING RELIEF of pain & inflammation1 BetaVet ® (betamethasone sodium phosphate & betamethasone acetate injectable suspension) is indicated for the control of pain and inflammation associated with osteoarthritis in horses.

Learn more at www.betavetequine.com or call 1-800-458-0163.

Please see Brief Summary of Full Prescribing Information on the following page.

INDICATION: BetaVet ® is indicated for the control of pain and inflammation associated with osteoarthritis in horses.

IMPORTANT SAFETY INFORMATION For Intra-Articular (I.A.) Use in Horses.

CONTRAINDICATIONS: BetaVet ® is contraindicated in horses with hypersensitivity to betamethasone. Intra-articular injection of corticosteroids for local effect is contraindicated in the presence of septic arthritis.

WARNINGS: Do not use in horses intended for human consumption. Clinical and experimental data have demonstrated that corticosteroids administered orally or parenterally to animals may induce the first stage of parturition when administered during the last trimester of pregnancy and may precipitate premature parturition followed by dystocia, fetal death, retained placenta, and metritis. Additionally, corticosteroids administered to dogs, rabbits and rodents during pregnancy have resulted in cleft palate in offspring and in other congenital anomalies including deformed forelegs, phocomelia and anasarca. Therefore, before use of corticosteroids in pregnant animals, the possible benefits to the pregnant animal should be weighed against potential hazards to its developing embryo or fetus. Human Warnings: Not for use in humans. For use in animals only. Keep this and all medications out of the reach of children. Consult a physician in the case of accidental human exposure.

PRECAUTIONS: Corticosteroids, including BetaVet ®, administered intra-articularly are systemically absorbed. Do not use in horses with acute infections. Acute moderate to severe exacerbation of pain, further loss of joint motion, fever, or malaise within several days following intra-articular injection may indicate a septic process. Because of the anti-inflammatory action of corticosteroids, signs of infection in the treated joint may be masked. Due to the potential for exacerbation of clinical signs of laminitis,

glucocorticoids should be used with caution in horses with a history of laminitis, or horses otherwise at a higher risk for laminitis. Use with caution in horses with chronic nephritis, equine pituitary pars intermedia dysfunction (PPID), and congestive heart failure. Concurrent use of other anti-inflammatory drugs, such as NSAIDs or other corticosteroids, should be approached with caution. Due to the potential for systemic exposure, concomitant use of NSAIDs and corticosteroids may increase the risk of gastrointestinal, renal, and other toxicity. Consider appropriate wash out times prior to administering additional NSAIDs or corticosteroids.

ADVERSE REACTIONS: Adverse reactions reported during a field study of 239 horses of various breeds which had been administered either BetaVet ® (n=119) or a saline control (n=120) at five percent (5%) and above were: acute joint effusion and/or local injection site swelling (within 2 days of injection), 15% BetaVet ® and 13% saline control; increased lameness (within the first 5 days), 6.7% BetaVet ® and 8.3% saline control; loose stool, 5.9% BetaVet ® and 8.3% saline control; increased heat in joint, 2.5% BetaVet ® and 5% saline control; and depression, 5.9% BetaVet ® and 1.6% saline control.

DOSAGE AND ADMINISTRATION: Shake well immediately before use. Use immediately after opening, then discard any remaining contents.

RX ONLY References: 1. Trotter GW. Intra-articular corticosteroids. In: McIlwraith CW, Trotter GW, eds.

Joint Disease in the Horse. Philadelphia: W.B. Saunders; 1996; 237–256.

BetaVet® and the Horse Head design are registered trademarks of American Regent, Inc. © 2019 American Regent, Inc. PP-BV-US-0027 5/2019

BRIEF SUMMARY OF PRESCRIBING INFORMATION (Betamethasone Sodium Phosphate and Betamethasone Acetate Injectable Suspension) 6 mg betamethasone per mL For Intra-Articular (I.A.) Use in Horses CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian.

INDICATION: BetaVet® is indicated for the control of pain and inflammation associated with osteoarthritis in horses.

DOSAGE AND ADMINISTRATION: Shake well immediately before use.

CONTRAINDICATIONS: BetaVet® is contraindicated in horses with hypersensitivity to betamethasone. Intra-articular injection of corticosteroids for local effect is contraindicated in the presence of septic arthritis.

WARNINGS: Do not use in horses intended for human consumption.

Clinical and experimental data have demonstrated that corticosteroids administered orally or parenterally to animals may induce the first stage of parturition when administered during the last trimester of pregnancy and may precipitate premature parturition followed by dystocia, fetal death, retained placenta, and metritis.

Additionally, corticosteroids administered to dogs, rabbits and rodents during pregnancy have resulted in cleft palate in offspring. Corticosteroids administered to dogs during pregnancy have also resulted in other congenital anomalies including deformed forelegs, phocomelia and anasarca. Therefore, before use of corticosteroids in pregnant animals, the possible benefits to the pregnant animal should be weighed against potential hazards to its developing embryo or fetus. Human Warnings: Not for use in humans. For use in animals only. Keep this and all medications out of the reach of children. Consult a physician in the case of accidental human exposure.

PRECAUTIONS: Corticosteroids, including BetaVet®, administered intra-articularly are systemically absorbed. Do not use in horses with acute infections. Acute moderate to severe exacerbation of pain, further loss of joint motion, fever, or malaise within several days following intra-articular injection may indicate a septic process. Because of the anti-inflammatory action of corticosteroids, signs of infection in the treated joint may be masked. Appropriate examination of joint fluid is necessary to exclude a septic process. If a bacterial infection is present, appropriate antibacterial therapy should be instituted immediately. Additional doses of corticosteroids should not be administered until joint sepsis has been definitively ruled out. Due to the potential for exacerbation of clinical signs of laminitis, glucocorticoids should be used with caution in horses with a history of laminitis, or horses otherwise at a higher risk for laminitis. Use with caution in horses with chronic nephritis, equine pituitary pars intermedia dysfunction (PPID), and congestive heart failure. Concurrent use of other anti-inflammatory drugs, such as NSAIDs or other corticosteroids, should be approached with caution. Due to the potential for systemic exposure, concomitant use of NSAIDs and corticosteroids may increase the risk of gastrointestinal, renal, and other toxicity. Consider appropriate wash out times prior to administering additional NSAIDs or corticosteroids.

ADVERSE REACTIONS: Adverse reactions reported during a field study of 239 horses of various breeds which had been administered either BetaVet® (n=119) or a saline control (n=120) were: acute joint effusion and/or local injection site swelling (within 2 days of injection), 15% BetaVet® and 13% saline control; increased lameness (within the first 5 days), 6.7% BetaVet® and 8.3% saline control; loose stool, 5.9% BetaVet® and 8.3% saline control; increased heat in joint, 2.5% BetaVet® and 5% saline control; depression, 5.9% BetaVet® and 1.6% saline control; agitation/anxiety, 4.2% BetaVet® and 2.5% saline control; delayed swelling of treated joint (5 or more days after injection), 2.5% BetaVet® and 3.3% saline control; inappetance, 3.4% BetaVet® and 2.5% saline control; dry stool, 1.7% BetaVet® and 0% saline control; excessive sweating, 0.8% BetaVet® and 0% saline control; acute non-weight bearing lameness, 0.8% BetaVet®and 0% saline control; and laminitis, 0.8% BetaVet® and 0% saline control.

PP-BV-US-0027_FullPg_Ad.indd 2

CLINICAL PHARMACOLOGY: Betamethasone is a potent glucocorticoid steroid with anti-inflammatory and immunosuppressive properties. Depending upon their physico-chemical properties, drugs administered intra-articularly may enter the general circulation because the synovial joint cavity is in direct equilibrium with the surrounding blood supply. After the intra-articular administration of 9 mg BetaVet® in horses, there were quantifiable concentrations of betamethasone (above 1.0 ng/mL) in the plasma.

EFFECTIVENESS: A negative control, randomized, masked field study provided data to evaluate the effectiveness of BetaVet® administered at 1.5 mL (9 mg betamethasone) once intra-articularly for the control of pain and inflammation associated with osteoarthritis in horses. Clinical success was defined as improvement in one lameness grade according to the AAEP lameness scoring system on Day 5 following treatment.

The success rate for horses in the BetaVet® group was statistically significantly different (p=0.0061) than that in the saline group, with success rates of 75.73% and 52.52%, respectively (back-transformed from the logistic regression).

ANIMAL SAFETY: A 3-week target animal safety (TAS) study was conducted to evaluate the safety of BetaVet® in mature, healthy horses. Treatment groups included a control (isotonic saline at a volume equivalent to the 4x group); 1X (0.0225 mg betamethasone per pound bodyweight; BetaVet®); 2X (0.045 mg betamethasone per pound bodyweight; BetaVet®) and 4X (0.09 mg betamethasone per pound bodyweight; BetaVet®). Treatments were administered by intra-articular injection into the left middle carpal joint once every 5-days for 3 treatments. Injection site reactions were the most common observations in all treatment groups. Injection site reactions were observed within 1 hour of dosing and included swelling at the injection site, lameness/stiffness of the left front limb, and flexing the left front knee at rest. The injection site reactions ranged from slight swelling (in many horses on multiple days in all treatment groups) to excessive fluid with swelling, pain, and lameness (4x group only). Injection site reactions were observed most commonly on treatment days, and generally decreased in number and severity over subsequent days. The incidence of injection site reactions increased after the second and third injection (number of abnormalities noted on day 10 > day 5 > day 0). In the BetaVet® treated groups the number and severity of the injection site reactions were dose dependent. The 4X BetaVet® group had the highest overall incidence of and severity of injection site reactions, which included heat, swelling, pain, bleeding, and holding the limb up at rest. The control group and 4X group (which received similar injection volumes) had a similar incidence of injection site reactions; however, the severity of reactions was greater in the 4X group. Absolute neutrophils were statistically significantly higher in the BetaVet® treated groups as compared to the control group. Trends toward a decrease in lymphocytes and eosinophils, and an increase in monocytes were identified in the BetaVet® treated groups after the initial dose of BetaVet®. Individual animal values for white blood cells generally remained within the reference range. BetaVet® treated horses also had a trend toward increased blood glucose after the initial dose. Some individual animals showed mild increases in blood glucose above the reference range.

SHAKE WELL BEFORE USING NADA 141-418, Approved by FDA For customer care or to obtain product information visit www.betavetequine.com or call 1-800-458-0163.

To report an adverse event please contact American Regent Animal Health at (800) 734-9236 or email pv@americanregent.com.

A Division of American Regent, Inc. 5 Ramsey Rd. | Shirley, NY 11967

5/17/2019 9:15:15 AM

NUTRITION

Effects of Nitrate on Reproductive Losses and Newborn Congenital Issues Epidemiological and research findings provided evidence to support the hypothesis that excessive nitrate was associated with reproductive losses, congenital hypothyroidism and musculoskeletal abnormalities in fetuses of mares and other animals. These fetal losses, with an unknown etiology, and associated with mare reproductive loss syndrome (MRLS), have plagued horse-farms in central Kentucky and elsewhere for decades.

Most fetal losses with an unknown etiology are related to environmental and climatic changes that affect pasture forages in the late spring and to a lesser extent in the early fall. During some foaling seasons, these reproductive losses may dramatically increase in late spring.

An extraordinary increase in abortions was first recognized as a syndrome in the late spring of 1980 after pasture forages were stressed by droughts, frosts and freezes, and affected pasture forages and diets were found to be elevated in nitrate. Fetal losses occur in mares grazing spring pastures that are affected by climatic and environmental factors, including droughts, cold-stress, nitrogenous fertilizers and herbicides. These factors, among others, cause nitrate to accumulate in pasture forages.

Since 1980, similar fetal losses were recognized each spring. However, in the spring of 2001, there was a massive unprecedented increase in fetal losses when several thousand mares acutely aborted in central Kentucky and surrounding areas. Cold-stress to pasture forages induced an acute spike in potassium and nitrate in damaged plants. Fetal losses, with an unknown etiology, that occurred after unseasonal climatic conditions in the late spring of 2001 were referred to as MRLS. Increased reproductive losses in mares were most numerous in early developing fetuses, but they occurred at all stages of gestation starting 9 to 10 days after pasture forages were severely stressed.

Nitrate increases in pasture forage within 24 to 48 hours after cold-stress and will remain elevated until plants recover with new growth. The syndrome is more common after unseasonal late spring erratic weather patterns of droughts and cold-stress to pasture forages.

Congenital abnormalities may occur in the um-

bilical cord and musculoskeletal system in affected fetuses that do not abort early in gestation when exposed to excessive nitrate. These are primarily limb contractures. Severe and fatal congenital anomalies represent a small percentage of fetal losses. However, minor limb contractures, umbilical cord and amnion lesions are common and often not fatal.

Musculoskeletal abnormalities account for significant losses in newborn foals and mares may die during parturition due to dystocia and foaling complications related to limb contractures. Developmental anomalies, including contracted foal syndrome, with an unknown etiology, have been affecting foals in central Kentucky and elsewhere for decades.

A Thoroughbred horse farm where mares were aborting due to suspected nitrate toxicosis and pathologic lesions consistent with MRLS, also had a herd of pregnant Boer goats that were grazing similar pastures. They developed severe congenital goiter due to nitrate-induced hypothyroidism. The gross and microscopic lesions in the affected kid goats were identical to those seen in kid goats from pregnant does grazing pastures previously fertilized with ammonium nitrate. Seemingly, the pregnant Boer goat and possibly other small ruminants are ideal sentinel herbivores to detect nitrate toxicosis and congenital hypothyroidism in less sensitive animals, such as affected foals that do not display any obvious clinical signs of goiter but do display remarkable lesions of congenital musculoskeletal abnormalities.

Shutterstock/Eric Isselee

By Thomas Walter Swerczek, DVM, PhD, and Alan Ray Dorton, DVM

ModernEquineVet.com | Issue 9/2019

17

NUTRITION

Without the simultaneous ter frosts and freezes. Seemingly, observations and findings with the combination of nitrate from pregnant Boer goats and pregnant pasture forages and supplemental mares consuming the same highfeedstuffs produced overwhelmnitrate pasture forages, it would ing nitrate toxicity. have been challenging to have Drastic unseasonal climatic made the association between changes that affect pasture fornitrate, reproductive losses, conages cannot be prevented, but genital hypothyroidism and muswhen they do occur, pasture grazculoskeletal abnormalities in foals ing time should be limited until Thomas Walter Swerczek, DVM, PhD that are less sensitive to the same pasture forages return to normal goitrogenic agent as kid goats. which may take 2 to 3 weeks beNitrate competes with iodide fore damaged plants and the niuptake by the thyroid and has trate returns to normal levels. Rebeen associated with alterations in ducing the protein in broodmare iodine metabolism, thyroid activrations and increasing sodium in ity and thyroid gland morphology the form of salt, which seemingly in several animal species. The obneutralized high levels of nitrate, vious difference between species were beneficial in reducing fetal how the thyroid gland responds losses associated with high nimorphologically to the apparent trate pasture forages. same goitrogenic agent is the reaIf mares are bred early before the son why nitrate toxicosis was not natural breeding season of April, previously associated with hypoMay and June, they may be prone thyroidism and musculoskeletal to fetal loss during the natural abnormalities in foals. breeding season if they are exposed Association between nitrate to toxic levels of nitrate from pastoxicosis and reproductive losses in mares and other ture forages and concurred high-protein supplemental herbivores is difficult to demonstrate that nitrate per diets. Mares that are bred before the natural breeding se is responsible for fetal losses and congenital deneed to be managed to prevent fetal loss during late fects. However, since thyroid function and thyroid spring when unseasonal climatic changes may occur. hormones are essential for early fetal development If early bred mares abort during the natural and maintenance of pregnancy explains why nitrate breeding season after endometrial cups form after 38 toxicosis is associated with hypothyroidism, reprodays of pregnancy to produce equine chorionic goductive losses and congenital defects. nadotropin, false pregnancy occurs and they will not Nitrate levels at the time of abortions, or birth may return estrus until endometrial cups disappear which be normal, but earlier in fetal development, nitrate may take several months.

MeV may be elevated to the extent it affects normal early About the authors thyroid function, which is essential for fetal developDr. Swerczek is a professor emeritus at the ment and maintenance of pregnancy and prevention University of Kentucky, College of Agriculture, of reproductive losses, congenital defects, including Food and Environment. Dr. Dorton is a private musculoskeletal abnormalities. veterinary practitioner in central Kentucky, who It was found in 1980 and again in 2001, if pregnant specializes in equine reproduction, and is also on mares were being supplemented with high-protein call for the Equine Research Farm, Department feedstuffs and/or high-protein alfalfa hay, they were of Veterinary Science, University of Kentucky. more likely to abort after pastures spike in nitrate af-

If bred early, mares may be prone to fetal loss if exposed to toxic levels of nitrate from their diets.

For more information: Swerczek TW, Dorton AR. Effects of nitrate and pathogenic nanoparticles on reproductive losses, congenital hypothyroidism and muscular abnormalities mares and other livestock: new hypotheses. Animal and Veterinary Sciences. 2019:7(1):1-11. Epub Feb. 13. http://www.animalvetsci.org/article/212/10.11648.j.avs.20190701.11 18

Issue 9/2019 | ModernEquineVet.com

COLIC

Colic Puts a Thoroughbred Down, But Not Out Monty, a 6-year-old Thoroughbred gelding, was down and displaying signs of colic when owner Ashley Aguado received the late-night call that he was sick. She rushed to him and found her three-day eventing horse in dire condition.

“When I arrived, Monty’s face was cut up from all the rolling he was doing,” said Ms. Aguado. “He was sweating and just didn’t look good overall.”

Ms. Aguado gave Monty a dose of flunixin to relieve pain associated with colic, but Monty’s condition was not improving. Having never experienced colic with her horses, she called Monty’s veterinarian and his trainer.

Due to the late hour, they suggested getting him to the University of California at Davis veterinary hospital immediately, as its Large Animal Clinic’s 24/7 emergency service was the only place that could help him.

Following the 1-hour drive to campus, Monty was immediately seen by the emergency veterinarians on duty.

As the clock approached midnight, Monty underwent a thorough examination that identified a distended small intestine during rectal palpation and an ultrasound examination, and the presence of red-tinged abdominal fluid collected during a belly tap. These findings, as well as the severe, refractory pain that Monty continued to exhibit, indicated he needed emergency surgery. During emergency colic surgery, equine emergency surgeons located and corrected an epiploic foramen entrapment, which is a type of intestinal strangulation. They had to remove 15 feet of Monty’s small intestine because it was irreversibly damaged and a jejunocecostomy was performed, in which the remaining small intestine was reat-

tached to empty into the cecum.

Monty seemed to recover well from surgery and spent a week under close monitoring in the ICU. However, six days after returning home, he became uncomfortable and stopped eating. Ms. Aguado wasn’t taking any chances, so she returned with Monty to UC Davis.

In rare cases, horses will colic again following colic surgery due to a variety of reasons that may be related or unrelated to the original surgery. Unfortunately, Monty did not respond to medical treatment and had to undergo another surgery. At the second surgery, a feed impaction at the previous jejeunocecostomy was found. The impaction was resolved by gentle massage and emptied through an incision in the small intestine. The jejunocecostomy site appeared functional but inflamed. To allow this site time to heal and reduce its swelling, a a jejunocolostomy was performed to allow feed to empty into the large intestine and bypass the previous site of impaction.

Monty’s recovery from the second surgery has been uneventful. He is on a strict diet of more pelleted feed than hay, and Ms. Aguado is allowing him several months to slowly return to competition. Now 9 months later, she is finally riding him again for the first time since the surgeries.

“We want to take it slow,” said Ms. Aguado. “There’s no need to rush anything, especially since he is such a young horse. We’ll take our time in producing him into a top-level eventer.”

Ms. Aguado acquired Monty 3 years ago when her previous eventing horse maxed out at the “training” level, which is only third on a scale of 7 levels in 3-day eventing.

Even though Monty is early in his athletic career, she feels he can go much further than the training level.

MeV

For more information about repeat colic surgery, read our July cover story.

ModernEquineVet.com | Issue 9/2019

19

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