The Modern
Equine Vet www.modernequinevet.com
Vol 11 Issue 9 2021
Are Event-Day Arrhythmias Common? A Look at Thyroid Supplementation What Makes You Feel Good at Work? Are Manicures Okay for Staff?
TABLE OF CONTENTS
COVER STORY
4 The Cross-Country Heart:
Just How Common Are Event-Day Arrhythmias? Cover: Shutterstock/mariait
NUTRITION
Purina Omolene Horse Feed Now Provides Gastric Support.........................................6 Using Nutrition to Boost the Immune System ....................................................................8 INFECTIOUS DISEASES
PCR Testing Could Improve EPM Diagnosis................................................13 Are Manicures Okay for Staff? .........................................................................14 Promising Treatment for MRSA Wound Infections ................................16 NEWS NOTES
Is Thyroid Supplementation Beneficial?.......................................................3 New Biomarker for Kidney Injury..................................................................12 What Makes You Feel Good at Work?...........................................................14
ADVERTISERS Epicur Pharma......................................................................................................3 Arenus Animal Health/Assure Gold.................................................................5 American Regent/Adequan...............................................................................7 Merck Animal Health .........................................................................................9
Arenus Animal Health/Aleira..........................................................................11 Arenus Animal Health/Releira........................................................................15 Arenus Animal Health/Assure Gold...............................................................17
The Modern
Equine Vet SALES: Matthew Todd • Matthew Gerald EDITOR: Marie Rosenthal ART DIRECTOR: Jennifer Barlow CONTRIBUTING WRITERS: Paul Basilio • 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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NEWS NOTES
Is Thyroid Supplementation Beneficial? Supra-physiologic thyroxine supplementation caused a decreased V200 during a standard exercise test and may result in cardiac arrhythmias, according to a recent study. The use of thyroid supplement is pervasive in athletic horses, although its effects on performance is unknown. U.S. and Canadian researchers wanted to know whether supra-physiologic doses of levothyroxine affect the velocities at which blood lactate was >4 mmol/L (VLa4) and heart rate was >150 (V150) and 200 (V200) beats per minute, respectively. Additionally, a survey of post-race blood samples was also collected to determine whether high thyroxine concentrations were common in racehorses. First, the researchers determined thyroxine (T4) concentrations in 50 post-race blood samples taken at a single Standardbred meet. T4 is a hormone produced by the thyroid gland and helps to control the rate of energy expenditures. Next, 6 healthy Standardbred racehorses were trained to fitness and then randomized to 1 of 3 treatments: carrier, 0.1 mg/kg thyroxine, or 0.25 mg/kg thyroxine for 2 weeks. Horses completed a standardized exercise treadmill test (SET) to fatigue on the last day of treatment. Serum
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free and total thyroxine and triiodothyronine were determined on the day of SET testing. Blood lactate and ECG data were collected during the SET at 6, 8, 10, 11, and 12 m/s and during recovery. The effect of treatment and SET on heart rate and blood lactate was examined. The median T4 value in the post-race blood samples was 2 µg/dL (reference range 1.5–4.5 µg/dL) and 3/50 horses (6%) and 8/50 (16%) had concentrations above and below the reference range, respectively. Levothyroxine at 0.25 mg/kg resulted in higher heart rates during the treadmill test (199 ± 30, 223 ± 17 and 239 ± 9 bpm at 6, 8 and 10 m/s, respectively) and recovery (144 ± 20 and 119 ± 15 at 5 and 15 min) as compared with placebo (176 ± 18, 203 ± 10 and 219 ± 6 beats/min at 6, 8 and 10 m/s and 126 ± 5, 102 ± 11 at 5–15 minutes, respectively). Three of 6 horses developed cardiac arrhythmias, including atrial fibrillation. MeV
For more information: Kritchevsky J, Olave C, Tinkler S, et al. A randomised, controlled trial to determine the effect of levothyroxine on Standardbred racehorses. Equine Vet J. 2021 Jun 8. https://doi.org/10.1111/evj.13480
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CARDIOLOGY
THE CROSSCOUNTRY HEART:
Just How Common Are Event-Day Arrhythmias?
Although falls and musculoskeletal injuries
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frequency and complexity as the competition level increased. “Our 2 primary questions were whether there were differences in arrhythmia frequency and type across different [competition] divisions, and whether there were any risk factors associated with the presence of the arrhythmias.”
The study
Following a thorough cardiac auscultation, the horses in the study were outfitted with small, modified base-apex (single) lead continuous ECGs. Arrhythmias were categorized by complexity (i.e., singles, couplets, triplets, or tachyarrhythmias), and
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Shutterstock/alexaldo
are still the leading causes of death of horses in the cross-country phase of eventing, there is a growing recognition of the importance of cardiovascular disease as a cause of sudden death. “Thankfully, sudden death is uncommon,” said Mary Durando, DVM, PhD, DACVIM, owner of the Equine Sports Medicine Consultants. “However, when it occurs, it is devastating and distressing for all involved.” To get ahead of the problem, the United States Eventing Association (USEA) established a cardiovascular task force to look at cardiac function in these horses. “In horses that are negative for post-mortem findings from these events, it’s often assumed—or at least thought—that there’s a contribution of arrhythmias,” she said in a virtual presentation during the 2021 ACVIM Forum. The task force’s hypothesis was that arrhythmias in healthy eventing horses would increase in
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CARDIOLOGY
the horses were grouped by breed. For statistical purposes, the horses were also divided into lower, intermediate and upper divisions based on their past performance. In addition to collecting information about the arrhythmias, the investigators also noted how long each horse had a heart rate (HR) >200 beats/min. A total of 131 horses were enrolled from events across the United States, but 56 ultimately had to be excluded from the study—39 had excessive ECG artifacts during the event, 16 failed to finish the event, and 1 had pre-existing atrial fibrillation.
The results
There were large differences in the average HRs for each division. Horses in division 1 averaged 176.3 beats/min, while division 3 averaged 199.7 beats/ min. The maximal HRs for each division were 196.5, 205.8 and 215.9 beats/min, respectively. Less than half of the horses in division 1 attained an HR of 200 beats/min, while all but 1 horse in division 3 had an HR of 200 beats/min or greater. “For the division 1 horses, an average of 13% of the cross-country event was spent with an HR of 200 beats/min or greater, whereas the horses in division 3 spent an average of 60% of the event time over 200 beats/min. In at least 1 horse, the HR was more than 200 beats/min for the entire event. To me, these findings illustrate the phenomenal difference in work between the divisions.” The arrhythmia findings shook out in a similar manner.
“In all of the arrhythmia categories, horses in division 1 had a lower frequency than horses in division 3,” Dr. Durando said. “No horses in division 1 or division 2 had complex arrhythmias, whereas 20% of horses in division 3 did.” In fact, horses in division 1 were 94% less likely to have an arrythmia and 98% less likely to fulfill the Martin criteria (more than 2 premature depolarizations) than the horses in division 3 were. Age and increasing maximal HR were 2 predictors of couplet arrhythmias, and the time the HR was >200 beats/min was a predictor of triplets and complex arrhythmias. Division was also significantly related to the severity of the arrhythmia. “We were surprised at the number of horses that had simple and complex arrhythmias during crosscountry,” Dr. Durando explained. “Around 56% had at least 1 premature depolarization during the event.” Dr. Durando’s team also discovered a critical need for better ECG-collecting technology. The set-up used in the study was not particularly well received by the riders, and reliability was an issue. “It would facilitate the collection of more data and gaining more information if we had a somewhat easier way of doing this,” she said. “[It is difficult] to collect ECGs from these horses when they're exercising so intensely. Cross-country is probably one of the hardest sports to try to do because of the motion artifact that you're going to get with horses going over jumps and changing speeds and riders.” MeV
Purina Omolene Horse Feed Now Provides Gastric Support The Purina Omolene horse feed lineup now contains the Outlast Gastric Support Supplement. This addition to the Omolene feed line provides gastric support in every meal, which benefits most horses. “Research shows up Anna Pesta, PhD to 90% of active horses are at risk for experiencing gastric discomfort,” said Anna Pesta, PhD, equine nutritionist for Purina Animal Nutrition. “Adding the Outlast supplement to Omolene horse feeds was a logical decision because it allowed us to provide the benefit of daily support of proper gastric pH to a wider variety of horses. 6
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Omolene feeds provide fuel for performance in any horse, from active pleasure to top equine athletes. This lineup of textured feeds also works well for horses that are picky eaters or who don’t eat pelleted feed, horses needing to gain weight, racehorses and horses with high caloric demands. Look for the Outlast Gastric Support Supplement seal on each of these Purina Omolene feeds: • 100 Active Pleasure: For horses in light to moderate work. • 200 Performance: For horses in competition, broodmares and yearlings. • 300 Mare & Foal: For foals, weanlings, yearlings and pregnant or lactating mares fed with foals. • 400 Complete Advantage®: For competition horses. • 5 00 Competition: For hard-working and endurance equine athletes. MeV
There’s nothing else like it. For more than 30 years, Adequan® i.m. (polysulfated glycosaminoglycan) has been administered millions of times1 to treat degenerative joint disease, and with good reason. From day one, it’s been 2, 3 the only FDA-Approved equine PSGAG joint treatment available, and the only one proven to. Reduce inflammation Restore synovial joint lubrication Repair joint cartilage Reverse the disease cycle When you start with it early and stay with it as needed, horses may enjoy greater mobility over a 2, 4, 5 lifetime. Discover if Adequan is the right choice. Visit adequan.com/Ordering-Information to find a distributor and place an order today. 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 1-888-354-4857 or email pv@americanregent.com. Please see Full Prescribing Information at www.adequan.com.
www.adequan.com 1 Data on file. 2 Adequan® i.m. Package Insert, Rev 1/19. 3 Burba DJ, Collier MA, DeBault LE, Hanson-Painton O, Thompson HC, Holder CL: In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondral defect model. J Equine Vet Sci 1993; 13: 696-703. 4 Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY. Articular chondrocyte apoptosis in equine osteoarthritis. The Veterinary Journal 2003; 166: 52-57. 5 McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse.St. Louis, MO: Elsevier, 2016; 33-48. All trademarks are the property of American Regent, Inc. © 2021, American Regent, Inc. PP-AI-US-0629 05/2021
NUTRITION
Using Nutrition Shutterstock/LiniaS
to Boost the Immune System Exercise is widely recognized as a stressor that can cause neuroendocrine and hormonal changes that weaken a horse’s immune system. For heavily exercised performance horses that are often transported long distances and kept near other horses, this can be a perfect recipe for compromised immunity. In addition to vaccination and infectious disease standard care, what more can be done to strengthen a horse’s natural defenses? “Research on the impact of diet on the immune system in the horse is in its infancy,” said Lori K. Warren, PhD, associate professor of equine nutrition at the University of Florida. “Unfortunately, we don't have a lot of hard facts and prescriptive recommendations.” She does, however, have some valuable insights B 8
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that she shared in a virtual session at the 66th Annual AAEP Convention.
Vitamins and Antioxidants
Vitamins and antioxidants support the immune system either through their antioxidant role or by contributing to the body’s natural defenses by strengthening epithelial barriers, cell-mediated immunity, or antibody production. Vitamin E is often studied for its role in mitigating exercise-induced oxidative stress, but there is a limited amount of literature on immune-related outcomes, she explained. Although studies do confirm the role of vitamin E in immune function and immune support, they are usually comparing the role
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Get the scoop on EPM RECOVERY
Effectively treating Equine Protozoal Myeloencephalitis (EPM) doesn’t have to be difficult. Reach for PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets • Goes to work fast (within 12 hours) — no loading dose required1 • The only FDA‑approved alfalfa‑based top dress treatment for EPM, proven safe and effective • No mess, no fuss ‑ easy to administer and highly palatable
Ask your Merck Animal Health Equine representative about PROTAZIL® or call 800-521-5767. IMPORTANT SAFETY INFORMATION: Use of PROTAZIL® (1.56% diclazuril) Antiprotozoal Pellets 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% diclazuril) Antiprotozoal Pellets with concomitant therapies in horses has not been evaluated. For use in horses only. Do not use in horses intended for human consumption. Not for human use. Keep out of reach of children. 2 Giralda Farms • Madison, NJ 07940 • merck-animal-health-usa.com • 800-521-5767 Copyright © 2021 Intervet Inc., d/b/a/ Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved.
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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
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- (4chlorophenyl)-4- (4,5-dihydro-3,5-dioxo1,2,4-triazin-2(3H )-yl)benzeneacetonitrile, has a molecular formula of C 17 H 9 CI 3 N 4 O 2 , 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 mLs of Weight Range mLs of of Horse (lb) Pellets of Horse (lb) Pellets 275 - 524 20 1275 - 1524 60 525 - 774 30 1525 - 1774 70 775 - 1024 40 1775 - 2074 80 1025 - 1274 50 -
One 2.4-lb bucket of PROTAZIL® will treat one 1274-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. falcatula in bovine turbinate cell cultures was studied by Lindsay and Dubey (2000).1 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 substantially exceed the in vitro IC 95 estimates for merozoite production (Dirikolu et al., 1999) 2. 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,
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.
of vitamin E supplementation vs. a diet deficient in vitamin E. “Evidence is lacking that feeding vitamin E above established requirements will confer any additional advantages in an otherwise healthy horse,” Dr. Warren said. “For horses in work, the vitamin E requirement ranges from 1.6 to 2 IU/ kg of body weight, which is about 1,000 IU per day for a 500-kg horse. In horses that have neurological disease or in those with myopathies, feeding vitamin E above these requirements is warranted.” Selenium is another key oxidant that is largely evaluated vs. a deficient diet. Horses typically require about 1 to 1.25 mg/ day for a 500-kg horse. While studies have shown declines in innate and acquired immunity in horses fed selenium-deficient diets, there has not been much work done on feeding above the requirements. Dr. Warren’s team performed a study
that compared a diet containing the National Research Council (NRC) requirement for selenium vs. one that contained 3 times the requirement. The horses were unfit at the beginning of the study, but they underwent 2 hours of strenuous exercise daily during the trial. “Muscle sampling revealed a greater antioxidant capacity and a reduction in lipid peroxidation products in the early post-exercise period when horses received the higher level of selenium,” she explained. “From an immune standpoint, higher selenium intake resulted in a more rapid remediation of the leukocytosis that we typically see following exercise.” She added that other immune measurements, such as lymphocyte proliferation and neutrophil function, were unaffected. “Collectively, these results suggest that selenium could be important in stressful situations or big challenges but feeding sele-
PREBIOTIC AND FUNCTIONAL FIBERS
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.
More than 70% of the immune system is associated with the gastrointestinal tract, and it serves as an important first line of defense against pathogens. Because horses are herbivores, the fibers are critical. Some dietary fiber, called prebiotics, colonizes the gut with beneficial bacteria, binding to pathogens to block attachment to the intestine and interacting directly and indirectly with immune cells associated with the gut mucosa. Others have probiotic effects include mannan-oligosaccharides (MOS), beta-glucans and pectin. These fibers are abundant in mare colostrum and milk. “As fibers are fermented and cleaved down to shorter oligosaccharides in the hind gut, they certainly can exert positive effects in that part of the GI tract,” Lori K. Warren , PhD said. “I think our interest is to try to supply these shorter fibers through the diet so that they can also exert their effect in the small intestine.” Recommending to clients that they feed their horse a diet high in fiber that supplies the functional fiber precursors is a solid first step toward enhancing the immune system. “Encourage the use of a variety of fiber sources, especially those that are high in water-soluble fiber, which are often referred to as highly digestible fiber,” she said. “We’re looking for things that contain beta-glucans— such as whole oats—and things that contain pectin, like beet pulp and soybean hulls. All of those are a good approach until we can learn more about the functional fibers in the horse.”
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 2.4-lb (1.1 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.
Shutterstock/ Katarzyna Hurova
FOR ORAL USE IN HORSES ONLY
NUTRITION
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:
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. Intervet Inc d/b/a Merck Animal Health 2 Giralda Farms, Madison, NJ 07940 Copyright © 2021 Intervet Inc. a subsidiary of Merck & Co. Inc. All rights reserved. 07-2014 211.x.3.0.3
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IN A WORLD OF ITS OWN
Researched Respiratory Support Researched and Proven as an aid in controlling IAD and RAO Recommended in the ACVIM Consensus Statement on Respiratory Disease (1)
(2)
Not all Omega 3’s are the same; use the Researched and Recommended 1500mg Purified DHA formulation. Your Clients Deserve The Best in a Non-Pharmaceutical Solution.
– Using the Best Matters References: [1] Nogradi N, Couetil LL, Messick J, Stochelski MA, Burgess JA. Evaluation of an Omega-3 Fatty Acid Containing Feed Supplement in the Management of Horses with Chronic Lower Airway Inflammatory Diseases. J Vet Intern Med 2015; 29:299-306. [2] Couetil LL, Cardwell J.M, Gerber V, Lavoie J.-P, Leguillette R, Richard E.A. Inflammatory Airway Disease of Horses. ACVIM Consensus Statement J of Vet Intern Med 2016; 30:503-515 p. 508-510.
Check with Arenus on how Aleira can help your equine patients effectively cope with respiratory and immune function disorders. See how Aleira can help you to reduce or eliminate pharmaceutical interventions.
Arenus Animal Health | 866-791-3344 | www.arenus.com
NUTRITION
nium above requirements is not likely to confer addition benefits under normal training conditions,” she said. And too much selenium can be toxic. In 2009, 21 polo ponies died after an overdose of selenium used to help muscle recovery. For vitamin C, there is plenty of research available, but the results have not demonstrated a clear benefit in reducing oxidative stress. There is no dietary requirement established for vitamin C, and it is assumed that synthesis of the vitamin in a horse’s body is enough to meet their needs.
Immunomodulation with Fatty Acids
Fatty acids have long been known to influence the immune response through several mechanisms, including gene expression, cell signals, cell membrane composition and by serving as a substrate for more
New AKI Marker Found Symetric dimethylarginine (SDMA) concentrations seem to correlate with creatinine concentrations in dehydrated horses, and they could be a biomarker for kidney injury. A prospective cohort study explored the correlation between SDMA and the level of dehydration against traditional renal biomarkers, as well as its prognostic use as a biomarker of early renal injury. Serum SDMA, creatinine and urea concentrations and renal function analysis were measured in 41 horses with dehydration at 4 points until 48 hours after admission. Horses were grouped into mildly, moderately and severely dehydrated groups. SDMA concentrations at admission correlated with creatinine concentrations (r=0.412; P <0.001). Differences in SDMA concentrations at admission were detected among dehydration levels but not between survivors and non-survivors. Significant correlations of SDMA concentrations with other markers of renal function analysis and shortterm outcome were not seen. Only 1 of the horses developed acute kidney injury, which made the evaluation of the predictive value of SDMA difficult. Use of SDMA as a prognostic biomarker warrants further research, the researchers said. MeV
For more information: Lo H-C, Winter JC, Merle R, Gehlen H. Symmetric dimethylarginine and renal function analysis in horses with dehydration. Equine Vet J 2021. https://beva.onlinelibrary.wiley.com/doi/10.1111/evj.13484
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bioactive molecules. Both omega-3 and omega-6 fatty acids are important to include in a horse’s diet in the proper balance. “Ultimately, it’s the balance of omega-6 and omega-3 fatty acids in the body—or really within the cell— that determines the overall response,” she said. Prior research has shown that omega-3 fatty acids can reduce markers of inflammation. However, prior research has also shown the opposite. “It generally takes a high supplementation rate— anywhere from 50 to 75 mg/kg of body weight—to elicit changes in markers of inflammation,” Dr. Warren explained. “That is much higher than is typically recommended by supplement companies, and probably too high to be economically sustainable for most horse owners.” She also explained that although omega-6 fatty acids are often maligned, they are by no means the villain in the fatty acid saga. “There have been claims that omega-6 fatty acids can cause inflammation, but there is little support for this in the literature.” In one of her studies, Dr. Warren found that yearlings supplemented with a high-fat source of either fish oil or corn oil—which is rich in omega-6—had similar reductions in the inflammatory marker PGE2 when compared with a diet where no fat was supplemented. “From a clinical standpoint, most people are interested in supplementing omega-3 fatty acids to horses with inflammatory conditions such as osteoarthritis,” she added. “A relatively high amount of EPA [eicosapentaenoic acid] and DHA [docosahexaenoic acid] from fish oil was shown to alter the fatty acid composition of synovial fluid in several studies, but it’s been a mixed bag in terms of having an impact on inflammatory markers or clinical outcomes.” She added that omega-3 supplementation in healthy horses typically has no benefit. The American College of Veterinary Internal Medicine has recommended 1.5 g of DHA for the treatment of inflammatory airway disease, but those recommendations are quite lower than the dosages that affect inflammatory markers in the literature, according to Dr. Warren. Omega-3 fatty acids appear to have the greatest impact in horses that have a heavy inflammatory load, which echoes some of the effects that are found in antioxidant nutrients. “It does appear that the longer-chain omega-3 fatty acids, such as EPA and DHA and their sources, are more effective than supplying omega-3 as the parent fatty acid alpha-linolenic acid. However, there’s not enough research for me to able to systematically arrive at an effective dose that I can pass along,” she said. MeV
INFECTIOUS DISEASES
PCR Testing Could Improve EPM Diagnosis By Adam Marcus The use of real-time polymerase chain reaction (rPCR) testing could help veterinarians more accurately diagnose horses with equine protozoal myeloencephalitis (EPM), particularly in animals that have not previously received treatment for the infection, researchers found. The study, by Pedro N. Bernardino, DVM, MS, and his colleagues The study, done by Pedro N. Bernardino, DVM, MS, and his colleagues at the University of California, Davis, School of Veterinary Medicine, at the University of California, Davis, School of Veterinary Medicine, showed that DNA from Sarcocystis neurona—a leading cause of damage to the central nervous system in horses—was detectable in cerebrospinal fluid (CSF) using real-time PCR. The test appeared to be effective even in animals whose fluid samples lacked intrathecally derived antibodies to S. neurona. However, PCR testing was less accurate in horses previously treated for protozoal infection, according to the researchers. Caused by the consumption of contaminated opossum feces, EPM is a widespread but uncommon condition in horses, affecting an estimated 1% of animals in the United States that are exposed to the organism that causes the infection, according to the American Association of Equine Practitioners.
Tricky Diagnosis
Symptoms of EPM include loss of coordination, gait issues, paralysis of the muscles in the head, seizures and other clinical signs that may also characterize other disorders. What’s more, no specific test exists for the disease, making diagnosis complicated. In animals suspected of having EPM, veterinarians often order a spinal tap, an invasive procedure that carries a risk of infection and other complications and which also is prone to contamination by blood. Antibody testing of the blood also can reveal both active infection and past exposure to S. neuroma. For the study, Dr. Bernardino’s group assessed the accuracy of rPCR testing in 210 samples of CSF taken from horses with a suspected diagnosis of EPM. Of those, 25 animals tested positive for S. neuroma
DNA using rPCR alone and 30 horses had intrathecally derived antibodies to S. neurona only, the researchers reported. Thirteen horses with a positive rPCR test of their spinal fluid also had antibodies in their intrathecal fluid, they said. “These results suggest that previous treatment with antiprotozoal drugs eliminates S. neurona in the [cerebrospinal fluid] or makes its DNA undetectable. …,” the researchers reported. “An alternative explanation could be that horses with no history of antiprotozoal treatment were more likely to be acutely infected with S. neurona compared to horses experiencing chronic disease, suggesting that disease chronicity can play a role in the usefulness of [real-time] PCR as a diagnostic tool.” Nicola Pusterla, DVM, PhD, a professor of medicine and epidemiology at UC Davis, and the senior author of the study, said rPCR will not replace serological testing but rather would be best used as an adjunct test in specific cases of neurologic illness in horses. These include animals with clinical symptoms associated with EPM, those with an early onset of disease and those that have not received antiprotozoal drugs and that do not have antibodies in their CSF. “In such cases it is sometimes possible to detect S. neurona DNA,” he told Modern Equine Vet. “While we mostly rely on immunodiagnostics (antibody detection) to support a diagnosis of EPM using CSF antibody titers alone or serum/CSF antibody ratio, these tests are not 100% accurate,” Dr. Pusterla added. “On the other hand, CSF PCR is a very unreliable way to diagnose EPM, mostly because of the high rate of falsenegative results. The idea is to use a 2-tiered approach: collect serum and CSF and test for S. neurona. If the horse has signs of EPM and the serum/CSF ratio is in the diagnostic range, a diagnosis of EPM can be reached. However, if the same horse with clinical signs compatible with EPM has no evidence of antibodies in the CSF, it is warranted to test the CSF for S. neurona by PCR or to test for other protozoal parasites such as Neospora hughesia and Toxoplasma gondii. I must reinforce the concept that PCR is not a replacement for antibody detection in the field of EPM, it is just another tool that in some cases can shed light onto the diagnosis.” MeV
For more information: Bernardino P, et al. Molecular detection of Sarcocystis neurona in cerebrospinal fluid from 210 horses with suspected neurologic disease. Vet Parasitol. 2021;291:109372. https://www.sciencedirect.com/science/article/abs/pii/S0304401721000327?via%3Dihub
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INFECTIOUS DISEASES
Shutterstock/ Eshma
Are Manicures Okay for Staff? By Adam Marcus Gel polish might be murder on fingernails, but it appears safe for use in surgical settings. Groups like the Association of periOperative Registered Nurses have said that health care facilities should create their own policies regarding their staff ’s use of nail polish, citing a lack of evidence showing that polishes either promote or reduce the risk for infection. A 2020 study in Oncology Nursing Forum of 87 nurses found that freshly painted nails harbored less bacteria than unpolished nails, although the protection waned over time. For a new study, Stacy L. Anderson, DVM, MVSc, PhD, dean and professor in the College of Veterinary Medicine at Lincoln Memorial University in Harrogate, Tenn., and her colleagues offered 40 female health care professionals and students free manicures.
All of the women received a split treatment: 5 fingernails were coated with gel polish, and 5 had no coating. The goal was to determine if the polish would reduce the viability of bacteria on the fingers after scrubbing before surgical procedures. The answer wasn’t, ahem, a nail biter: According to Dr. Anderson’s group, gel polish appeared to have no effect on bacterial loads (P=0.09). However, the researchers did find that longer fingernails did seem to harbor more bacteria, as measured by colony forming units, after scrubbing. “The main point equine practitioners should take home is that nail length is the single most important factor in the ability to perform an adequate surgical hand scrub,” Dr. Anderson told Modern Equine Vet. “Keeping nails less than 2 mm in length allows for more effective hand scrubbing techniques—and likely hand-washing techniques—regardless of application of nail polish to the fingernails.” MeV
For more information: Anderson SL, Wisnieski L, Achilles SL, et al. The impact of gel fingernail polish application on the reduction of bacterial viability following a surgical hand scrub. Vet Surg 2021 Aug 3.doi: 10.1111/vsu.13703. https://cjon.ons.org/file/54391/download • https://www.aorn.org/guidelines/clinical-resources/clinical-faqs/hand-antisepsis-hygiene
What Makes You Feel Good at Work? Appreciation and relationships help make veterinarians feel good at work, according to a new study (Vet Rec 2021 Apr 5 05 April 2021 https://doi.org/10.1002/ vetr.54, https://bvajournals.onlinelibrary.wiley.com/ doi/10.1002/vetr.54). Researchers investigated what brings pleasure to your job. “By focusing on what contributes to vets experiencing positive emotions, we can better understand how to improve the well-being of those who care for our beloved pets, livestock and wildlife,” said Madeleine Clise, PhD, a psychologist and adjunct lecturer at the University of Adelaide’s School of Psychology In a questionnaire completed by 273 Australian veterinarians, participants were asked to provide up to 10 responses to the prompt, “I derive pleasure 14
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from my work as a veterinarian When...’. More than 2,500 responses were categorized for both positive and negative aspects of your job. Positive relationships between you and your clients and colleagues was a more frequent response than positive relationships with animals. “Veterinarians, just like all of us, feel good when they are shown trust and respect. And a simple ‘thank you’ goes a long way,” she said. Other findings from the survey suggested that having opportunities to use and develop your specialized skillsets, a positive workplace culture, successful outcomes with patients and opportunities to collaborate with colleagues were also important for career satisfaction. MeV
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INFECTIOUS DISEASES
Promising Treatment for MRSA Wound Infections Treating wounds with the secretion of a type of stem cell effectively reduced the viability of methicillinresistant Staphylococcus aureus (MRSA), according to a new study from researchers at the Baker Institute for Animal Health, Cornell University College of Veterinary Medicine. Moreover, the secretion stimulated the surrounding skin cells to build up a defense against the bacterial invader, the researchers found. “The results showed that secreted factors from equine mesenchymal stromal cells (MSCa)—a type of stem cell—significantly decreased the viability of MRSA in our novel skin model,” said first author Charlotte Marx, PhD, a postdoctoral researcher in the lab of corresponding author Gerlinde R. Van de Walle, DVM, PhD, associate professor of microbiology and immunology at Cornell. “Moreover,” Dr. Marx said, “we demonstrated that equine MSC secretions increase the antimicrobial activity of the skin cells by stimulating immune responses of the surrounding resident skin cells. “Horses were used for the study because—in both horses and humans—particular types of chronic wounds are often therapy-resistant and cause complications, leading to high morbidity and mortality,” Dr. Van de Walle said. The team began by establishing an equine skin biofilm model. Biofilms are communities of microorganisms that develop on surfaces. In this state, bacteria are well protected against antibiotics even if they are not resistant. The skin samples were cultured over 3 days from the skin of horses that had to be euthanized for reasons unrelated to the study. During the culturing period, cell death and epidermal thickness remained stable. Next, the research team created an infected wound model by making uniform wounds in the skin samples and inoculating them with either MRSA or its antibiotic-sensitive counterpart, methicillin-sensitive S. aureus (MSSA). The wounds were then treated for 24 hours with either antibiotics, plain medium that acted as a control in the experiment, or MSC secretome. At the end of the treatment period, the researchers measured bacterial load by evaluating colony-forming units per gram of tissue.
MRSA has become a major health care problem because these bacteria can become threatening under certain circumstances, such as in immunocompromised patients or in infected wounds, and because they have grown resistant to many antibiotics. The study may point to a possible new approach for treating MRSA. While many people carry MRSA without serious consequences, this superbug can be fatal for those whose health is compromised. The key is MSCs—stem cells that can be isolated from bone marrow, fat, blood and other tissues. “Initially, the use of MSCs for tissue regeneration was advocated based on their ability to differentiate into various tissue types,” Dr. Van de Walle said. “For this reason, it was anticipated that injected MSCs colonize the injury site, differentiate into the appropriate tissue type and regenerate the damaged tissue.” However, studies are revealing that only a small portion of administered MSCs actually incorporate into injured tissue, she said. “For this reason, it is becoming generally accepted that the beneficial effects in tissue repair and regeneration are more likely indirect, depending on the effects of what these cells secrete,” Dr. Van de Walle said. “Such cell-free therapies might prove safe and potentially more advantageous alternatives by overcoming the risks and obstacles associated with the use of the cells themselves.” Although MSCs have been shown to reduce inflammation in multiple studies, the Cornell study went further, investigating the effect of the MSC secretion—also known as the secretome—on the antimicrobial defense mechanisms of skin cells and testing its efficacy on biofilms in a physiologically relevant equine skin model. The findings contribute to the understanding of the MSC secretome’s antimicrobial properties and further support the value of MSC secretome-based treatments for infected wounds, Dr. Marx said. “By identifying additional effective treatments,” she said, “we can contribute to reducing the use of antibiotics in both veterinary and human medicine, which is important for the fight against antibiotic resistance.” MeV
For more information: Marx C, Gardner S, Harman RM, et al. Mesenchymal stromal cell-secreted CCL2 promotes antibacterial defense mechanisms through increased antimicrobial peptide expression in keratinocytes. Stem Cell Transl Med. 2021 Sept. 16. DOI: 10.1002/sctm.21-0058. https://stemcellsjournals.onlinelibrary.wiley.com/doi/10.1002/sctm.21-0093
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