The Modern Equine Vet - June 2019 by The Modern Equine Vet

The Modern

Equine Vet www.modernequinevet.com

Vol 9 Issue 6 2019

Diagnosing Equine Coronavirus Equine Surveillance of Infectious Diseases Diagnosing Peridontal Disease Do Dewormers Affect the Microbiome?

NEW FEATURE: ASK THE NUTRITIONIST? YOUR NUTRITION QUESTIONS ANSWERED

TABLE OF CONTENTS

COVER STORY

4 Diagnosing Equine Coronavirus

Cover photo: Shutterstock/Pascale Gueret

ASK THE NUTRITIONIST?

What to feed an insulin-resistant patient that is underweight...................................... 7 INFECTIOUS DISEASE

Equine Surveillance Changes Understanding of Common Respiratory Diseases...................................................................................................12 DENTISTRY

Look, Probe, Stage: Diagnosing Periodontal Disease........................................................16 NEWS

Rectal Fluids May Be Alternative to IV fluids.......................................................................... 3 Deworming Drugs Appear to Leave Gut Microbiome Unscathed..................................10 Chlorhexidine Better Than Alcohol Rubs; Rubbing Better Than Brush Scrubbing for Hand Sanitation......................................................................................14 Maternal Enrofloxicin May Not Affect Fetal Cartilage.......................................................15 ADVERTISERS AVMA | PLIT....................................................................3 Heska..............................................................................5 Purina Sponsored Content.................................7 Shanks Veterinary Equipment..................................8

Merck Animal Health..................................................9 American Regent Animal Health...........................11 Stokes Healthcare......................................................13 Avalon Medical...........................................................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

Issue 6/2019 | ModernEquineVet.com

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.

NEWS NOTES

Rectal Fluids May Be Alternative to IV fluids Rectal fluid administration may offer an effective, inexpensive alternative or adjunct to IV fluid therapy, particularly when administration via nasogastric tube is not possible or contraindicated, according to a study out of the United Kingdom. In the randomized, controlled, crossover study the researchers from Australia and England compared the use of rectally administered fluids to nasogastric and IV administration. Six healthy horses each received 1 of 3 different fluid treatment protocols (IV Hartmann's, nasogastric polyionic solution and rectally administered tap water) at 5 mL/kg/h and also underwent a control protocol (no treatment) while feed and water were withheld for 6 hours. There was a minimum 2-week washout period between each treatment. Prior to administering rectal fluids, the rectum was manually evacuated and a 24 French flush enema tube inserted about 50 cm into the rectum and secured to the tail.

Fluid was delivered continuously by gravity flow. The researchers measured packed cell volume (PCV), total solids (TS), albumin, electrolytes, lactate, urine-specific gravity, vital parameters, gastrointestinal borborygmi and central venous pressure every 2 hours. They found that all of the horses tolerated the rectal administration of fluid. PCV decreased over time with all fluid treatments but not with the control, and TS decreased with IV and rectally administered fluid. There was an increase in gastrointestinal borborygmi with rectally administered fluid. MeV

For more information: Khan A, Hallowell GD, Underwood C, et al. Continuous fluid infusion per rectum compared with intravenous and nasogastric administration in horses. Equine Vet J. 2019 Mar 22 (Epub ahead of print). https://onlinelibrary.wiley.com/doi/10.1111/evj.13113

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INFECTIOUS DISEASE

Diagnosing Equine

CORONAVIRUS B y

M a r i e

R o s e n t h a l ,

M S

Although more U.S. horses are testing posi-

tive for equine coronavirus (ECoV), a newly described enteric disease, U.S. veterinarians do not have a lot of information about how horses present and what their prognosis likely will be. Luckily supportive treatment, which can include nonsteroidal anti-inflammatories and fluids, is usually what most horses require, as most infections are self-limiting. However, fatalities, endotoxemia and hyperammonemia have occurred, especially among miniature horses, which may be more susceptible to severe disease. Most cases involve adult horses in boarding stables or competitive facilities.

Since 2010, when the United States started testing for the virus, the number of cases has been rising in the United States, although that could be attributed to better awareness leading to more testing rather than an increase in the disease, according to Nicola Pusterla, DrMedVet, MedVet, DACVIM, a professor of medicine and epidemiology at the School of Veterinary Medicine, University of California, Davis. Timing of symptom onset is an important clue as the disease tends to occur from October to April. Dr. Pusterla and his colleagues compared the case management of ECoV in 33 adult horses (12 mares, 20 geldings and 1 stallion) that presented to the UC Davis Veterinary Medical Teach Hospital with 33 negative horses (15 mares, 17 geldings and 1 stallion) to get some idea of the management of these horses. The disease was diagnosed using a positive real-time quantitative polymerase chain reaction (qPCR) tests for ECoV on feces from the horses, which presented from March 1, 2012 to March 31, 2018. In total, they tested 498 adult 4

Issue 6/2019 | ModernEquineVet.com

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Imaging the Possibilities

Photo courtesy of UC Davis

INFECTIOUS DISEASE

Dr. Nicola Pusterla talks with veterinary students about equine infection.

horses by qPCR to find the study horses. The positive horses were between 2 and 37 years old, and the negative horses were between 1 and 30 years old. Three of the positive horses had co-infections.

Most presented with a history of fever, and a little less than half had anorexia and colic, which one would expect with an enteric disease. “One of the issues with ECoV is that only 20% of horses display enteric signs, such as colic and/or diarrhea. This

means that most horses show more generic, signs such as fever, lethargy and anorexia,” Dr. Pusterla told The Modern Equine Vet. “Knowing this, most veterinarians are more likely to pursue an infection of the respiratory tract, rather than a gastrointestinal tract infection,” he said. “Both nasal secretions and feces can be sent to a diagnostic lab for further diagnostics and a twostep approach can be instituted, meaning running nasal secretions for respiratory pathogens via PCR and if the panel is negative, add ECoV [testing] on the feces,” Dr. Pusterla said. Twenty-seven of the positive horses were hospitalized, and 26 survived to discharge. Most of the hospitalized horses required intensive care to resolve metabolic disContinued on page 8

What Feed Should You Recommend for Patients? Less than optimal nutrition can lead to disease or poor performance. But what should you recommend as the optimal equine diet for each horse?

Get help with our new nutrition column, written in partnership with Purina Equine Nutrition.

Email your questions to Marie, and the equine nutrition experts at Purina will find answers.

SPECIAL ADVERTISING SECTION

Ask the

Nutritionist

B Y K E L LY V I N E YA R D, M S , P h D

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.

Shutterstock/Timur Abasov

Most of my insulin-resistant patients are overweight, but occasionally I see an underweight insulin-resistant horse. What feeding recommendations can I make to help support weight gain in these horses? When feeding the non-obese, insulin-resistant horse, the foundation of the diet should be free-choice, good quality forage that is low in soluble carbohydrates (≤10–12% starch + water-soluble carbohydrates or WSC). The best way to confirm carbohydrate content is to send a sample to a forage testing lab. However, if that’s not possible, simply soak hay for 30 minutes in warm water or 60 minutes in cool water and drain immediately prior to feeding. Soaking hay reduces the soluble carbohydrate content by approximately 30% to 40%. Contrary to common belief, alfalfa hay is lower in soluble carbohydrates than most cool season grass hays (i.e. orchardgrass, timothy), averaging 10.6% starch + WSC . Incorporating some straight alfalfa hay or alfalfa cubes into these horses’ diets works well for weight gain. Additionally, providing free-choice access to hay can help maintain good body condition, especially if the horse is restricted from grazing. Other ways to support weight gain include: • Supplement with ½ –2 cups/day of vegetable oil. • Add non-molassed beet pulp—up to approximately 3 lbs. per day so as not to unbalance the ration.

• Feed a lower NSC commercial concentrate (i.e. Purina® WellSolve L/S®). Look for sugar and starch to be guaranteed on the tag at 10% to 20% starch+sugar and feed at appropriate amounts for weight gain. • Feeding small, frequent meals will help to further limit glycemic/insulinemic response; feeding at least 3 meals per day, if not more, is preferred for IR horses on a weight gain ration.

ABOUT THE AUTHOR Dr. Kelly Vineyard is a Senior Nutritionist, Equine Technical Solutions, with Purina Animal Nutrition. She is responsible for providing expert technical nutrition advice and insights in a variety of areas, including new product innovation and research and veterinarian and customer technical support. SPONSORED BY PURINA ANIMAL NUTRITION

ModernEquineVet.com | Issue 6/2019

INFECTIOUS DISEASE Continued from page 6 turbances, severe leukopenia and loid A, which was evaluated in 3 Signs of Equine Coronavirus the systemic inflammation that ECoV horses and 4 controls, was was seen, according to the reelevated in all of the houses. AzoAnorexia searchers. temia was present in 3 positive Most of the positive horses and 2 negative horses. Blood amColic lived in a multi-horse facility. monia concentrations performed Depression Five of the positive horses had in 3 horses with ECoV were withbeen to a show within the three in normal limits. Bile acids were Diarrhea or soft feces weeks before presenting. Most of analyzed in 1 horse with ECoV, Fevers around 40° C the negative horses were housed and they were elevated. at a facility with an open herd Horses positive for ECoV Inappetence and only 2 had a history of travel. had significantly lower total Only 7 of the positive horses white blood cell counts, neuLethargy trophil and lymphocyte counts had loose manure or diarrhea. than negative horses. There were no significant differences in the number of Ultrasound examination yielded no significant findhorses with small or large intestinal abnormalities or in ings in 19 horses with ECoV. lactate, protein, nucleated cell count or results of serum There was no significant difference in survival to disbiochemistry profiles between the 2 groups. Serum amycharge between positive and negative horses. About half of the positive horses were still shedding the virus when they were retested within 8 days after admission. Besides being a retrospective study, the researchers said the timing of the qPCR could have been a limiting factor of the study results. While qPCR appears to be the most sensitive fecal test for ECoV, false-negatives can occur if samples are submitted too early in the course of disease, the researchers explained. Because of the cost, fecal qPCR tests typically are performed once rather than serially, therefore, some of the controls could have been could have been false-positives, which may which may have affected some of the statistical results, the researchers said. “ECoV infection should be a differential diagnosis for adult horses with fever, colic, anorexia and leukopenia,” the researchers wrote. MeV

For more information:

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Issue 6/2019 | ModernEquineVet.com

Berryhill EH, Magdesian KG, Aleman N, et al. Clinical presentation, diagnostic findings, and outcome of adult horses with equine coronavirus infection at a veterinary teaching hospital: 33 cases (2012–2018). Vet J. 2019;248:95-100. https://www.sciencedirect.com/science/article/pii/ S1090023318303289?via%3Dihub Pusterla N, Vin R, Leutenegger CM, et al. Enteric coronavirus infection in adult horses. Vet J. 2018 Jan;231:13-18. doi: 10.1016/j.tvjl.2017.11.004. Epub 2017 Nov 20. For information about qPCR testing at UC Davis, go to https://pcrlab.vetmed.ucdavis.edu/veterinarydiagnostics/veterinary-submission-formsdiagnostictests-and-panels

The Science of Convenient Protazil® (1.56% diclazuril) is the only FDA-approved alfalfa-based top dress antiprotozoal pellet for the treatment of EPM. • Equine Protozoal Myeloencephalitis (EPM) is a serious neurological disease that can strike anytime, anywhere. Make treatment easy with Protazil® • Safe and accurate dosing with a calibrated scoop • Easier to use than paste, less stress for you and your horse • Rapid absorption — no loading dose required1 Now that’s convenient.

Ask your veterinarian for Protazil®. Visit us at Protazil.com to learn more about Merck Animal Health and the equine products and programs that help keep horses healthy. Use of Protazil® (1.56% dicazuril) is contraindicated in horses with known hypersensitivity to diclazuril. Safe use in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. The safety of Protazil® (1.56% dicazuril) with concomitant therapies in horses has not been evaluated. See related page in this issue for details. For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children.

The Science of Healthier Animals 2 Giralda Farms • Madison, NJ 07940 • merck-animal-health-usa.com • 800-521-5767 Copyright © 2018 Intervet Inc., d/b/a/ Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved. 3894 EQ-FP AD Protazil®

Hunyadi L, Papich MG, Pusterla N. Pharmacokinetics of a low-dose and DA-labeled dose of diclazuril administered orally as a pelleted top dressing in adult horses. J of Vet Pharmacology and Therapeutics (accepted) 2014, doi: 10.111/jvp.12176. The correlation between pharmacokinetic data and clinical effectiveness is unknown

ANTIPROTOZOAL PELLETS

NEWS NOTES

(1.56% diclazuril)

FOR ORAL USE IN HORSES ONLY For the treatment of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona in horses. CAUTION Federal (U.S.A.) law restricts this drug to use by or on the order of a licensed veterinarian. NADA #141-268 Approved by FDA DESCRIPTION Diclazuril, (±)-2,6-dichloro-α-(4-chlorophenyl)-4-(4,5 dihydro-3,5-dioxo-1,2,4-triazin-2(3H)-yl) benzeneacetonitrile, has a molecular formula of C17 H 9 CI 3 N4O2, a molecular weight of 407.64, and a molecular structure as follows:

Diclazuril is an anticoccidial (antiprotozoal) compound with activity against several genera of the phylum Apicomplexa. PROTAZIL® (diclazuril) is supplied as oral pellets containing 1.56% diclazuril to be mixed as a top-dress in feed. Inert ingredients include dehydrated alfalfa meal, wheat middlings, cane molasses and propionic acid (preservative). INDICATIONS PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets are indicated for the treatment of equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona in horses. DOSAGE AND ADMINISTRATION Dosage: PROTAZIL® (1.56% diclazuril) is administered as a top dress in the horse’s daily grain ration at a rate of 1 mg diclazuril per kg (0.45 mg diclazuril/lb) of body weight for 28 days. The quantity of PROTAZIL® necessary to deliver this dose is 64 mg pellets per kg (29 mg pellets/ lb) of body weight. Administration: To achieve this dose, weigh the horse (or use a weigh tape)). Scoop up PROTAZIL® to the level (cup mark) corresponding to the dose for the horse’s body weight using the following chart: Weight Range of Horse (lb) 275 - 524 525 - 774 775 - 1024 1025 - 1274

mLs of Pellets 20 30 40 50

Weight Range of Horse (lb) 1275 - 1524 1525 - 1774 1775 - 2074 -

mLs of Pellets 60 70 80 -

One 2-lb bucket of PROTAZIL® will treat one 1100-lb horse for 28 days. One 10-lb bucket of PROTAZIL® will treat five 1100-lb horses for 28 days. CONTRAINDICATIONS Use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets is contraindicated in horses with known hypersensitivity to diclazuril. WARNINGS For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children. PRECAUTIONS The safe use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets in horses used for breeding purposes, during pregnancy, or in lactating mares has not been evaluated. The safety of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets with concomitant therapies in horses has not been evaluated. ADVERSE REACTIONS There were no adverse effects noted in the field study which could be ascribed to diclazuril. To report suspected adverse reactions, to obtain a MSDS, or for technical assistance call 1-800-224-5318. CLINICAL PHARMACOLOGY The effectiveness of diclazuril in inhibiting merozoite production of Sarcocystis neurona and S. 1 falcatula in bovine turbinate cell cultures was studied by Lindsay and Dubey (2000). Diclazuril inhibited merozoite production by more than 80% in cultures of S. neurona or S. falcatula treated with 0.1 ng/mL diclazuril and greater than 95% inhibition of merozoite production (IC 95 ) was observed when infected cultures were treated with 1.0 ng/mL diclazuril. The clinical relevance of the in vitro cell culture data has not been determined. PHARMACOKINETICS IN THE HORSE The oral bioavailability of diclazuril from the PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets at a 5 mg/kg dose rate is approximately 5%. Related diclazuril concentrations in the cerebrospinal fluid (CSF) range between 1% and 5% of the concentrations observed in the plasma. Nevertheless, based upon equine pilot study data, CSF concentrations are expected to 2 substantially exceed the in vitro IC 95 estimates for merozoite production (Dirikolu et al., 1999) . Due to its long terminal elimination half-life in horses (approximately 43-65 hours), diclazuril accumulation occurs with once-daily dosing. Corresponding steady state blood levels are achieved by approximately Day 10 of administration. EFFECTIVENESS Two hundred and fourteen mares, stallions, and geldings of various breeds, ranging in age from 9.6 months to 30 years, were enrolled in a multi-center field study. All horses were confirmed EPM-positive based on the results of clinical examinations and laboratory testing, including CSF Western Blot analyses. Horses were administered PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets at doses of 1, 5, or 10 mg diclazuril/kg body weight as a top-dress on their daily grain ration for 28 days. The horses were then evaluated for clinical changes via a modified Mayhew neurological scale on Day 48 as follows: 0. Normal, neurological deficits not detected. 1. Neurological deficits may be detectable at normal gaits; signs exacerbated with manipulative procedures (e.g., backing, turning in tight circles, walking with head elevation, truncal swaying, etc.). 2. Neurological deficit obvious at normal gaits or posture; signs exacerbated with manipulative procedures. 3. Neurological deficit very prominent at normal gaits: horses give the impression they may fall (but do not) and buckle or fall with manipulative procedures. 4. Neurological deficit is profound at normal gait: horse frequently stumbles or trips and may fall at normal gaits or when manipulative procedures were utilized. 5. Horse is recumbent, unable to rise. Each horse’s response to treatment was compared to its pre-treatment values. Successful response to treatment was defined as clinical improvement of at least one grade by Day 48 ± conversion of CSF to Western Blot-negative status for S. neurona or achievement of Western Blot-negative CSF status without improvement of 1 ataxia grade. Forty-two horses were initially evaluated for effectiveness and 214 horses were evaluated for safety. Clinical condition was evaluated by the clinical investigator’s subjective scoring and then corroborated by evaluation of the neurological examination videotapes by a masked panel of three equine veterinarians. Although 42 horses were evaluated for clinical effectiveness, corroboration of clinical effectiveness via videotape evaluation was not possible for one horse due to missing neurologic examination videotapes. Therefore, this horse was not included in the success rate calculation. Based on the numbers of horses that seroconverted to negative Western Blot status, and the numbers of horses classified as successes by the clinical investigators, 28 of 42 horses (67%) at 1 mg/kg were considered successes. With regard to independent expert masked videotape assessments, 10 of 24 horses (42%) at 1 mg/kg were considered successes. There was no clinical difference in effectiveness among the 1, 5, and 10 mg/kg treatment group results. Adverse events were reported for two of the 214 horses evaluated for safety. In the first case, a horse was enrolled showing severe neurologic signs. Within 24 hours of dosing, the horse was recumbent, biting, and exhibiting signs of dementia. The horse died, and no cause of death was determined. In the second case, the horse began walking stiffly approximately 13 days after the start of dosing. The referring veterinarian reported that the horse had been fed grass clippings and possibly had laminitis. ANIMAL SAFETY PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets were administered to 30 horses (15 males and 15 females, ranging from 5 to 9 months of age) in a target animal safety study. Five groups of 6 horses each (3 males and 3 females) received 0, 5 (5X), 15 (15X), 25 (25X) or 50 (50X) mg diclazuril/kg (2.27mg/lb) body weight/day for 42 consecutive days as a top-dress on the grain ration of the horse. The variables measured during the study included: clinical and physical observations, body weights, food and water consumption, hematology, serum chemistry, urinalysis, fecal analysis, necropsy, organ weights, gross and histopathologic examinations. The safety of diclazuril top-dress administered to horses at 1 mg/kg once daily cannot be determined based solely on this study because of the lack of an adequate control group (control horses tested positive for the test drug in plasma and CSF). However, possible findings associated with the drug were limited to elevations in BUN, creatinine, and SDH and less than anticipated weight gain. Definitive test article-related effects were decreased grain/top-dress consumption in horses in the 50 mg/kg group. In a second target animal safety study, PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets were administered to 24 horses (12 males and 12 females, ranging from 2 to 8 years of age). Three groups of 4 horses/sex/group received 0, 1, or 5 mg diclazuril/kg body weight/day for 42 days as a top-dress on the grain ration of the horse. The variables measured during the study included physical examinations, body weights, food and water consumption, hematology, and serum chemistry. There were no test article-related findings seen during the study. STORAGE INFORMATION Store between 15°C to 30°C (59°F to 86°F). HOW SUPPLIED PROTAZIL® (1.56 % diclazuril) Antiprotozoal Pellets are supplied in 2-lb (0.9 kg) and 10-lb (4.5 kg) buckets. REFERENCES 1. Lindsay, D. S., and Dubey, J. P. 2000. Determination of the activity of diclazuril against Sarcocystis neurona and Sarcocystis falcatula in cell cultures. J. Parasitology, 86(1):164–166. 2. Dirikolu, L., Lehner, F., Nattrass, C., Bentz, B. G., Woods, W. E., Carter, W. E., Karpiesiuk, W. G., Jacobs, J., Boyles, J., Harkins, J. D., Granstrom, D. E. and Tobin, T. 1999. Diclazuril in the horse: Its identification and detection and preliminary pharmacokinetics. J. Vet. Pharmacol. Therap. 22:374–379. May 2010 Intervet Inc. 56 Livingston Ave, Roseland, New Jersey 07068 © 2010 Intervet Inc. All rights reserved. 08-10 211.x.3.1.0

Deworming Drugs Appear to Leave Gut Microbiome Unscathed By Adam Marcus Treating horses with drugs to kill parasitic worms does not significantly alter their gastrointestinal microbiome, although the effect may be greater for individual animals, researchers have found. Previous research has examined the effects of anthelmintic therapy on the equine microbiota; however, those studies were conducted in horses with diagnosed infections, not healthy animals. For the new work, researchers at Colorado State University and the University of Kentucky treated 10 horses with a single dose of Quest Plus (Zoetis), an anthelmintic drug that combines moxidectin and praziquantel. Using stool samples before and after therapy, they found that the number of bacterial species in the animals’ feces—known as alpha diversity—fell by a small but statistically significant amount (P<0.05). The researchers also identified 21 bacteria whose abundance changed before and after treatment; 7 species increased, while 14 decreased. Some of the microbes that increased in abundance, particularly Clostridiales in the Firmicutes phylum, have been associated with equine colic. When the researchers examined betadiversity, which reflects differences in abundance of species pre- and post-therapy, they did not find a marked effect. “Beta diversity is a measure of how different or similar two ecological communities are,” said Stephen Coleman, PhD, the director of the equine genetics laboratory at Colo-

rado State, in Ft. Collins, who helped conduct the research. “If we had seen a difference in beta diversity following treatment with the anthelmintic, it could have been interpreted to mean that the drugs had impacted the composition of the microbial communities.” But the data indicated that the changes in alpha and beta diversity were relatively small. “Broadly, this means that the anthelmintic likely had little impact on the microbes—which is a good thing,” Dr. Coleman told Modern Equine Vet. “In the context of our study, breeders, vets and

"Broadly, this means that the anthelmintic likely had little impact on the microbes." Dr. Stephen Coleman owners can take away that a single dose of praziquantel/moxidectin is not likely to alter their horse’s GI microbiome. This is valuable as many breeders, owners and vets have dewormed horses in the absence of a helminth infection. “However,” he added, “The study is only a first step. We still need to investigate other anthelmintic drugs, dose levels and schedule of treatment, as these could have different impacts. We also need to investigate the impacts of the operational taxonomic units that were different following treatment. We don’t yet know what the impact of those changes might be.” MeV

For more information: Kunz IGZ, Reed KJ, Metcalf JL, et al. Equine fecal microbiota changes associated with anthelmintic administration. J Equine Vet Sci. 2019;77:98-106. https://www.sciencedirect.com/science/article/abs/pii/S0737080618306014 10

Issue 6/2019 | ModernEquineVet.com

There’s nothing else like it. Over the past 30 years, Adequan® i.m. (polysulfated glycosaminoglycan) has been recommended millions of times1 to treat degenerative disease, and with good reason. From day one, it’s been 2, 3 the only FDA-Approved equine PSGAG joint precription available, and the only one proven to. Restore synovial joint lubrication Repair joint cartilage Reverse the disease cycle Reduce inflammation 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. Please see Full Prescribing Information at 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. Adequan and the Horse Head design are registered trademarks of American Regent, Inc. © 2019, American Regent, Inc. PP-AI-US-0222 2/2019

INFECTIOUS DISEASE

Equine Surveillance

CHANGES UNDERSTANDING OF COMMON RESPIRATORY DISEASES Through December 2018, equine herpesvirus 4 (EHV-4) was the most common cause of upper respiratory infection (URI) among horses, according to the Equine Respiratory Biosurveillance Program, which began more than 10 years ago. Since that time, more than 8,200 equine samples have been collected from around the country. The comprehensive, ongoing national surveillance study managed by Merck Animal Health and the University of California, Davis, monitors EHV-1 and EHV-4, equine influenza virus (EIV) and Streptococcus equi, which have been tracked from the inception of the program, and equine rhinitis A/B viruses (ERAV/ ERBV), added in 2012.

EIV Strains

DISEASE INCIDENCE 2008–2018

(AS A PERCENTAGE OF TOTAL POSITIVE SAMPLES)

Source: Merck Animal Health

33%

28%

22% 9%

EHV-4 EHV-4 makes up 33% of all positive samples and is the most commonly diagnosed infectious upper respiratory disease.

EIV

S.EQUI

EHV-1

Through December 2018, EHV-4 comprised 33% of all positive samples, followed closely by EIV at 28% and S. equi at 22%. The program has enabled a greater understanding of the demographic and signalment parameters associated with common URIs in horses, including recognition that age does not define susceptibility to certain pathogens. For example, EIV is no longer considered primarily a young horse disease; and EHV-4 can cause respiratory disease in mature horses as well as in weanlings and yearlings. Nicola Pusterla, DrMedVet, MedVet, DACVIM, who was integral to the Respiratory Biosurveillance

Issue 6/2019 | ModernEquineVet.com

Program’s design and implementation and leads the UC Davis Equine Infectious Disease Research Laboratory where program samples are analyzed, said the program is a testament to the value of pursuing diagnostic testing and disseminating that information. “When we started this program, we had no idea how much we would gain over this period,” Dr. Pusterla said. “The study has increased awareness of respiratory pathogens in the veterinary community, provided invaluable epidemiological information pertaining to common and less characterized respiratory pathogens and provided sequencing of EIV isolates to monitor how the virus is changing in the field and to evaluate and improve the efficacy of vaccines.” “One of the more notable findings of the program has been the frequency of equine influenza, and our analysis of constantly changing field isolates resulted in the discovery of a clinically relevant new equine influenza strain,” said D. Craig Barnett, DVM, Merck Animal Health director of equine veterinary professional services and program cofounder. The study houses one of the largest collections of EIV isolates ever gathered in the United States, demonstrating the high prevalence of the virus within the general horse population. “Prior to implementation of this study, we commonly heard from veterinarians that they weren’t seeing much influenza in horses. But throughout the study we’ve been tracking a lot of influenza even in well-vaccinated horses, regardless of age and breed. We continue to see a lot of EIV circulating—it was the most common disease in November 2018 and again in January 2019.” In 2018, Merck Animal Health launched the updated Prestige vaccine line containing a new influenza strain, Florida ’13, which was identified and isolated through the biosurveillance program. “Influenza outbreaks in well-vaccinated horses are generally indicative of significant antigenic drift and inadequate protection,” Dr. Barnett added. “Phyloge-

netic analysis and sequencing of the Florida ’13 strain confirmed that significant antigenic drift had indeed occurred and that this isolate was significantly different from viruses contained in current vaccines.”

Strangles and Herpesvirus

The data also found a higher than expected frequency of S. equi among nontraveling pleasure horses and a higher median age than in horses with other URIs. Strangles is the most commonly diagnosed URI in horses 6-10 years of age. They also found a propensity for co-infection with EHV-4, a major URI threat particularly—but not exclusively—in young horses, according to the data. The surveillance also showed that lesser known her-

pesviruses—EHV-2 and EHV-5—are often a source of co-infection with other major respiratory pathogens. The program “has been invaluable in improving our diagnostic capability,” said Christine Cocquyt, DVM, DACVIM, internal medicine associate with Tennessee Equine Hospital, a longtime participant. “We have been able to quickly and accurately assess potential outbreaks of disease, which has allowed us to quarantine and implement appropriate biosecurity programs when necessary.” Dr. Barnett added, “The program has changed the way we look at equine respiratory pathogens and helped the industry evolve the way it identifies and manages these costly diseases, not only through timely and accurate diagnostic services, but also with improved vaccination solutions and disease management measures.” MeV

For more information: Pusterla N, Kass PH, Mapes S, et al. Surveillance programme for important equine infectious respiratory pathogens in the USA. Vet Rec. 2011 (Epub Jun 15) doi: 10.1136/vr.d2157. https://veterinaryrecord.bmj.com/content/169/1/12.long2011. Findings from the Merck Animal Health Equine Respiratory Biosurveillance Program are being reported biweekly through the Equine Disease Communication Center (EDCC) at www.equinediseasecc.org/news.

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NEWS NOTES

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Chlorhexidine Better Than Alcohol Rubs; Rubbing Better Than Brush Scrubbing for Hand Sanitation Alcohol-based hand rubs (ABR) did not decrease bacterial log10 colony forming unit (CFU) counts more effectively than chlorhexidine (CHx) products, according to a recent study. In addition, the researchers found that when using CHx soaps in the equine setting, rubs are as effective as a brush scrubbing technique. This is good news for veterinarians in the field, because they can sanitize their hands more easily in the field. Currently, the World Health Organization recommends the use of alcohol-based hand rubs (ABR) for surgical hand preparation in human surgery. When disinfecting soaps are used, a rubbing technique causes less skin irritation than brush scrubbing. Based on a recent survey, most equine surgeons still use disinfecting soap. This prospective clinical trial compared the efficacy of four surgical hand preparation techniques (three rubs and one scrub) and compared the reduction of aerobic bacterial counts from pre- to post-preparation (immediate efficacy) and at the

end of surgery (sustained efficacy). The four techniques used were a hand scrub with 4% chlorhexidine gluconate soap (CHx scrub), a hand rub with 4% chlorhexidine gluconate soap (CHx rub), a hand rub with 61% ethanol solution with 1% chlorhexidine gluconate (CHx/ET), and a hand rub with a mixture of 30% 1-propanol and 45% 2-propanol solution (IPO). The clinicians participating in equine surgical procedures were enrolled during an 18-month study period and were not blinded to hand preparation technique. Techniques were assigned randomly and a wash out period of approximately 3 days given between them. Samples were collected by the glove juice technique after 1-minute of a neutral soap hand wash (pre-preparation), following completion of the randomly assigned hand preparation technique (post-preparation), and finally at the end of surgery (post-surgery). Aerobic bacterial log10 CFU counts were performed.

Most equine surgeons still use disinfecting soap, but chlorhexidine rubs were effective in sanitizing hands. A total of 228 hands from 7 clinicians were sampled in 109 surgical procedures. Immediate mean bacterial log10 CFU reduction was 2.4 for CHx-scrub, 2.8 for CHx-rub, 3.1 for CHx/ET rub and 2.1 for IPO rub. CHx/ET rub resulted in significantly lower bacterial counts than CHx-scrub and IPO rub, while CHxrub resulted in significantly lower counts than IPO rub. At the end of surgery, bacterial counts were the lowest for CHx-rub, significantly lower than CHx/ET rub (P<0.001) and IPO rub (P<0.001). There was no difference between CHx-rub and scrub techniques. MeV

For more information: Biermann NM, McClure JT, Sanchez J., et al. Prospective, randomised clinical trial of four different presurgical hand antiseptic techniques in equine surgery. Equine Vet J. 2018 Dec. 17 (Epub ahead of print). https://onlinelibrary.wiley.com/doi/10.1111/evj.13060 14

Issue 6/2019 | ModernEquineVet.com

Maternal Enrofloxicin May Not Affect Fetal Cartilage Although enrofloxacin can be detected in the fetus and fetal fluid after administration to late-term mares, it did not result in detectable effects on foal cartilage, according to a recent study. Researchers investigated the concentration of the fluoroquinolone antibiotic in pregnancy fluids when administered during late-term pregnancy, in addition to assessing the effect on fetal articular cartilage. Sixteen healthy pregnant mares at 260 days gestation were randomly placed into 1 of 3 groups: 1. control (no treatment; n = 3), 2. IV enrofloxacin 5 mg/kg (recommended therapeutic dose; n = 7) and 3. IV enrofloxacin 10 mg/kg (supratherapeutic dose; n = 6). The enrofloxacin was administered once daily for 11

days. Amniotic and allantoic fluid were sampled on days 1, 5 and 11, and blood samples were obtained daily. On day 11, the researchers induced by manual cervical dilation, and the fetuses euthanized following delivery. Fetal articular cartilage was examined macroscopically and histologically for lesions. Concentrations of enrofloxacin in samples were measured by liquid chromatography-tandem mass spectrometry. They found that enrofloxacin reached fetal circulation and accumulated in the pregnancy fluids, reaching the minimum inhibitory concentrations for common pathogens in all fluids. No differences were seen in fetal serum biochemistry values between the control and treatment groups. No lesions were noted on gross inspection of any fetal articular surface, and no major abnormal findings were observed on histological evaluation. MeV

For more information: Ellerbrock RE, Canisso IF, Roady PJ, et al. Diffusion of enrofloxacin to pregnancy fluids and effects on fetal cartilage after intravenous administration to late pregnant mares. Equine Vet J. 2018 Nov. 18 (Epub ahead of print). https://onlinelibrary.wiley.com/doi/10.1111/evj.13044

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DENTISTRY

Look, Probe, Stage:

Diagnosing Periodontal Disease B

Typical diastema and subsequent periodontal disease between two maxillary cheek teeth

Tools of the trade • Sedatives (detomidine and butorphanol) • Head stand or dental halter • Dental speculum • Head lamp or other oral light source • Dental mirror or oral endoscope • Periodontal probe • Alligator forceps • Local anesthesia (mepivacaine and butterfly catheters) • Radiograph machine • Dental chart Issue 6/2019 | ModernEquineVet.com

211 with a fracture and subsequent periodontal disease. The problem is always under the organic matter.

About 7 years ago, Matt Evans, DVM, of the Austin Equine Hospital in Driftwood, Texas, went to a dentistry lecture and realized his equine oral examinations weren’t quite where they should be. “I wasn’t really doing oral examinations at all,” he said. “I realized that I was going to have to change, so I bought a mirror and a probe and I had to start using them.” As it turns out, he found a lot

Periodontal probe with gradated measurements

of periodontal disease. Periodontal disease of the cheek teeth doesn’t grab as many headlines as colic or laminitis, but its ubiquitous nature and relative absence in the literature can leave practitioners in limbo while creating a treatment plan. Up to 85% of horses have some form of periodontal disease, and it’s responsible for 75% of all cheek teeth extractions in private practice.

Quantifying the problem

“The 2 ways we quantify any pathology in the horse is to do it objectively and based on the lit-

erature,” Dr. Evans said. The problem is that much of the literature is based on expert opinion—a decent basis for a treatment program, but not quite as reliable as evidence-based medicine. There is reason for optimism, however, as more researchers are refining their focus. For example, 1 group is investigating the microbial pathogens involved in equine periodontal disease and the most common causes, such as food-packing between the teeth.

The oral exam

Historical findings are generally nondescript. When Dr. Evans sees periodontal disease of the cheek teeth in a horse, the only common historical finding is that the owner asked for a dental exam. “If you’re finding outward physical examination findings such as swelling, sinusitis and fistulas, then the periodontal disease is pretty longstanding and severe,” he said. A dental chart, a good mouth

speculum, and a mirror are essential for the exam (See Tools of the Trade). “If you don’t own a mirror, then you’re probably not diagnosing much periodontal disease,” Dr. Evans explained. You’ll also need some way to remove the debris from the pockets. Some studies have shown that debriding with anything over 15 psi will drive debris and bacteria further into the wound. The pockets will be clean, but damage will be done. “Periodontal disease can be markedly painful,” Dr. Evans noted. “After I started looking [for periodontal disease], I realized that all the horses that I thought just didn’t like me actually had painful mouths. When I was putting my hands, the mirror, or a float in their mouth, I was causing a lot of pain.” He explained that if a horse appears painful during the examination or treatment, then stop and take a look—sedation may need to be increased. While it is more invasive, mepivacaine can be used distal or caudal to the area. Dr. Evans places local anesthesia in the palatal ridges or the buccal/lingual gingival reflection using a 23-gauge butterfly catheter attached to a 3 mL syringe. He places 20 mg of mepivacaine in two or three locations, distal to the lesion. “You’ll have an easier time cleaning out, probing, and examining the pocket,” he added. Dr. Evans spoke at the 64th Annual AAEP Convention in San Francisco.

All the mouth’s a stage

In addition to a proper dental chart, quantifying the periodon-

Table 1. Tooth Mobility Index STAGE MI0 MI1 MI2 MI3

DEGREE OF MOBILITY Mild normal Represents the first distinguishable sign of movement greater than normal Moderate movement of up to approximately 3 mm Severe movement >3 mm in any direction and/or is depressible

Table 2. Gingival Index STAGE GI0 GI1 GI2 GI3

EXAMINATION FINDINGS Normal gingiva Mild inflammation; slight color changes; slight edema; no bleeding on probing Moderate inflammation; redness; edema; and glazing; bleeding on probing Severe edema

Table 3. Periodontal Disease Index STAGE PD0 PD1

DEGREE OF ATTACHMENT LOSS Normal Gingivitis; no bone loss; probing depth <5 mm

PD2 PD3 PD4

Early PD; <25% attachment loss Moderate PD; 25%-50% attachment loss Advanced PD; >50% attachment loss

tal disease involves some staging (see Tables). Radiographs will be needed for the Periodontal Disease Index. It can be difficult to gauge when a horse has severe enough periodontal disease to warrant radiographs, so Dr. Evans uses several measurements. While a pocket depth of 5 mm is considered normal, that measurement does not consider the other 2 planes of reference. He uses a combination of the Tooth Mobility Index (Table 1), the Gingival Index (Table 2), and the

measured size of the lesion. Together with any clinical signs and presenting complaints, he can then decide how aggressively to pursue the lesions. “If I have a horse with a history of quidding and facial swelling, large pocket depths, tooth mobility, and a concerned owner, then I am going to be pretty aggressive about what I am going to recommend,” he explained. “If I have a clinically normal horse with no medical history and a smaller periodontal pocket, then I may not push any next steps.” MeV

For more information: Klugh D. Principals of periodontal disease. In: Klugh D. Principles of Equine Dentistry, 1st ed. London, UK: Manson Publishing, 2010;11. Wiggs RB, Lobprise HB. Basics of orthodontics. In: Veterinary Dentistry, Principles and Practice. Philadelphia: Lippincott-Raven, 1997;435-481. ]

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