The Modern
Equine Vet www.modernequinevet.com
Running on Empty
Evaluating Breeding Stallions The Long Riders: Transportation Injuries Making Flu Vaccination Easier UC Davis Gets PET Scanner: See Images Technician Update:
In Plain Site: Corneal Injuries
Vol 6 Issue 12 2016
Table of Contents
reproduction
Running on Empty: 4 Evaluating Stallion Soundness Cover photo: Shutterstock/mariait
Infectious Diseases
Suspensory injuries in National Hunt Horses...................................................................10 technician update
In Plain Site: Corneal Issues in Arabian Mares.................................................................14 News
New Applicator Makes Giving Equine Influenza Vaccine Easier ....................................... 3 Transportation-related Injury............................... 9 UC Davis Gets Equine PET Scanner..................13
advertisers Shanks Veterinary Equipment.................................. 3 Merck Animal Health.................................................. 5 Standlee Premium Western Forage......................... 7
Avalon Medical............................................................. 8 Electric Hoof Knife....................................................... 9 AAEVT............................................................................15
The Modern
Equine Vet Sales: Matthew Todd • ModernEquineVet@gmail.com Editor: Marie Rosenthal • mrosenthal@percybo.com Art Director: Jennifer Barlow • jbarlow@percybo.com contributing writerS: Paul Basillo • Kathleen Ogle COPY EDITOR: Patty Wall Published by PO Box 935 • Morrisville, PA 19067 Marie Rosenthal and Jennifer Barlow, Publishers percybo media publishing
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Issue 12/2016 | ModernEquineVet.com
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News notes
New Applicator Makes Giving EIV Vaccine Easier Merck Animal Health unveiled the New Flu Avert IN intranasal applicator at the annual meeting of the American Association of Equine Practitioners. The applicator makes vaccination easier and delivers enhanced mucosal coverage within the nasal cavity. “Flu Avert is special, in part, because of its unique intranasal application, and veterinarians have long recognized the benefits of Flu Avert for its exceptional influenza protection,” said Bryant Craig, DVM, Merck equine veterinary technical services manager. “However, previous applicators could be difficult to use as many horses didn’t appreciate the 6-inch cannula being inserted into their nasal cavity.” The new applicator, which is only 1-inch long, is administered from just inside the ventral nares and is hardly noticeable to the horse. It atomizes the vaccine into a very fine mist, delivering it in a much smaller particle size than with other applicators. This allows the vaccine to reach further into the nasal cavity and cover a broader area of the nasal and pharyngeal mucosa. “The difficulty of administration has been removed from the discussion, and no one can argue with the data behind Flu Avert and its efficacy,” said Erica Lacher, DVM, from Springhill Equine in Newberry, Fla., who was part of a group of veterinarians who studied the new applicator. The fine mist makes it much less traumatic for the horse, and it’s incredibly easy to administer, she added. “A horse’s comfort with a veterinary procedure is a function of how painless and positive we can make it,” said Sue McDonnell, MS, PhD, founding head of the equine behavior program at the University of Pennsylvania’s New Bolton Center, who conducted clinical studies with the new applicator and presented her findings during an AAEP session. She told the Modern Equine Vet that veterinarians should add positive reinforcement when administering the vaccine to increase acceptance. “That first experience is so important. If you’re doing 100 horses you’re probably going to have some who are somewhat surprised by it or it’s not completely positive. But it seems like with a treat out of your hand or a food pan while you’re doing it, many of them even look like they didn’t recognize that anything was going on. “A non-confrontational treatment protocol that incorporates minimal restraint along with positive reinforcement, distraction and/or reward for compliance can efficiently get almost every horse to accept mildly aversive health care procedures.” Continued on page 11
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reproduction
Running on
Empty? Evaluating the Stallion for Soundness
The general framework for the breeding sound-
ness examination (BSE) has not changed much since the Society for Theriogenology published the Stallion Manual in 1983. That framework is crucial, even with the incredible advances in technology today, according to Charles C. Love, DVM, PhD, DACT, of the section of Theriogenology at Texas A&M. “The BSE is simply an evaluation at a single moment in time,” Dr. Love said. “This is particularly important regarding spermatogenesis. We don’t know what happened in the horse a month before the test, or even the day before. We don’t know how the horse is going to be managed after the evaluation.” Test results may have a significant economic impact for the owner and those results are related directly to a veterinarian’s ability to perform the test, he said at the BEVA Congress here in Birmingham, England.
Low libido is an obvious limiting factor in how well a stallion will breed. A stallion in the presence of a mare in heat should show interest, demonstrate the Flehmen response and achieve an erection almost immediately. “Also take note of the subtle behavior changes,” Dr. Love explained. “One of the most common presentations is anejaculation or infrequent ejaculation. There are a variety of reasons why stallions can react this way, ranging from a primary physical problem to iatrogenic causes, such as a dislike of the person handling the artificial vagina.” Dr. Love related a story of a patient that was unable to be collected. The stallion had good posture, a flexed
B y 4
Issue 12/2016 | ModernEquineVet.com
P a u l
Shutterstock/mariait
Behavior
B a s i l i o
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 © 2016 Intervet Inc., d/b/a/ Merck Animal Health, a subsidiary of Merck & Co., Inc. All rights reserved. 3290 EQ-FP AD Protazil®
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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
reproduction (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
neck and normal thrusting motions, but no ejaculation occurred. Subsequent collections using a phantom showed that the stallion would fall off the mare in such a way that suggested a primary neurologic problem. For this reason, Dr. Love recommends that veterinarians videotape collections as often as possible. “When you are in position during collection, you often don’t have any perspective on how the horse is really acting aside from the anejaculation,” he said. “Looking at the videotape from far away can give you an idea of what is happening.”
Physical Examination
For most veterinarians, the evaluation of the penis occurs while it is being washed. This can be a cursory method of evaluation that can lead to missed lesions. “I had a patient with a very long penis that could not ejaculate,” Dr. Love said. “On further evaluation, I noticed bruising and open lesions over the penis. This horse had been collected using a short
Missouri-model artificial vagina, and the penis repeatedly came into contact with the funnel portion. When he flared, it caused the bruising. After switching to a longer model, the horse did well.” The acute damage from such lesions may only be half of the problem in these horses. Older, chronic trauma can cause scarring over the glans penis. When the area dilates and flares, the scarred, inelastic tissue can cause pain and bleeding. This can lead to a stallion that simply does not want to ejaculate.
Scrotal Evaluation
A superficial evaluation of the scrotum for lesions and to make sure it is freely moveable is typically the first step, but Dr. Love does not put much weight behind how the testes feel on palpation. “It can vary considerably within a normal range,” he said. “On a hot day in Texas, a stallion’s testicles will be quite soft. If I were to evaluate that horse immediately prior to breeding then they may be al-
Ready for Retirement A common question for young racehorses coming off of the racetrack is at what size they will likely begin to produce sperm efficiently. “When testicular size reaches approximately 160 cm3 for both testicles, then these horses start to produce a relatively efficient amount of sperm,” Dr. Love said. “This adds relevance to our measurements.” One of Dr. Love’s 4-year-old racehorse patients was found to have markedly small testicles after retirement, which had the potential to cause problems for future sales. After 1 month, the horse’s testicular size had almost doubled and his sperm quality improved. “Veterinarians typically recommend reevaluation in 2 to 3 months in patients like these, but some horses will show improvement before that time,” he said. “There is a lot of pressure to determine whether small testicle size is a temporary or permanent condition. You’ll likely be able to tell if there is going to be a change in testicular size in less than 2 or 3 months.”
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Issue 12/2016 | ModernEquineVet.com
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Try ultrasonography for measuring testicular volume. It's accurate and allows simultaneous evaluation of the testicular parenchyma. most rock hard, likely due to the increased blood flow to the testicle.” Dr. Love does pay attention to the cremaster muscle, however. Some horses may have testicles that ride high, even in the summer. This has been reported in bulls with hyperplastic cremaster muscles that keep the testicles close against the body wall. “It’s an unusual finding, but it should be noted,” he explained. “A horse in mid-summer should have
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testicles that are well descended in the scrotum. If they ride too high and the testicles are kept against the body wall, then that may dramatically affect spermatogenesis.”
Testicular Volume
Dr. Love prefers to use ultrasonography for measuring testicular volume. The results are likely to be more accurate, and the modality allows for evaluation of the testicular parenchyma at the same time. “Testicles tend to not be perfectly horizontal,” he said. “They can have an upward slope. It’s important to make sure the probe is perpendicular to the axis of the testicle to get an accurate measurement of height.” For width, measure from the lateral surface to the medial surface of the testicle. Length tends to be the most challenging measurement. Dr. Love recommended measuring from the back of the testicle to the front, making sure to exclude the tail of the epididymis. Once the total volume is determined, then the veterinarian can determine the expected daily sperm output. MeV
News notes
The Long Riders: Transportation-Related Injury Horses being transported for longer than 24 hours are at greater risk for developing severe disease or death, according to an Australian survey. Barbara Padalino, DVM—a PhD candidate at the School of Animal and Veterinary Sciences, Charles Sturt University, Wagga Wagga, New South Wales, Australia—and her colleagues performed a cross-sectional online survey aimed to provide information about the risk factors for illness and injury associated with equine transportation. Of the 797 responses to the survey from both amateur and professional equestrians in Australia, all of whom transported horses at least monthly, there were 214 cases of a transportation-related health problem over the previous two years. There was a significant association between journey time and vehicle, and being transported by a commercial company. Trailers and non-commercial transporters were more commonly used for shorter journeys. Ten horses died during transit (two were found dead and the remaining eight were euthanized due to fractures). An additional 15 horses were euthanized within one week of the journey, seven of which occurred within 24 hours. Journey duration and breed were associated with transportation-related health problems. Compared with Standardbreds; Thoroughbreds, Arab and Warmblood horses were more likely to develop illness than be injured during transportation (P=0.001) than were Standardbreds. Compared with injuries, illness—including gastrointestinal and respiratory problems (23.8%, 33.7%, respectively) as well as death and euthanasia—were significantly associated with longer journey time (P<0.001). Respiratory disease was the most common problem and the risk increased with longer journey time. A little more than 16% suffered traumatic injury. Muscular problems were more likely to occur on an intermediate journey than a short one. There was no influence of journey duration on the incidence of heat stroke. Injuries were more likely to occur on shorter journeys. This is likely to be associated with behavioral problems or movement within the vehicle during the early part of the journey.
Transportation-related health problems are significantly associated with longer journey time, with illness more likely on journeys longer than 24 hours duration. Injuries more commonly occur on short journeys. MeV
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For more information: Padalino B, Raidal SL, Hall E, et al. Risk factors in equine transportrelated health problems: A survey of the Australian equine industry. Equine Vet J. 2016 Oct. 13. [Epub ahead of print]). http://onlinelibrary.wiley.com/doi/10.1111/evj.12631/full
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orthopedic
Suspensory Injuries in National Hunt Horses One-third of National Hunt race-
horses that were examined during a study had Grade 2 ultrasonographic abnormalities of the suspensory ligament branches (SLBs), although they had no clinical signs of injury. Alison Fairburn, BVSc, of the School of Clinical Veterinary Science at the University of Bristol in the United Kingdom, and her colleagues performed a cross-sectional study of 62 horses at a single National Hunt training yard to investigate the prevalence of subclinical ul-
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trasonographic abnormalities of the SLBs. They also wanted to establish cross-sectional areas of SLBs in the National Hunt population. Horses with a history of suspensory ligament injury or any abnormality detected on palpation during veterinary examination were excluded from the study. A standardized set of 10 images of the SLB were obtained for the forelimbs of each horse, which were assessed by three clinicians who were blinded as to which horse’s im-
age they were viewing. A previously reported grading system was used to score each site from 0 to 3, with the highest scores from each site being used to formulate a “branch grade.” The cross-sectional area (CSA) at each site was also measured and a mean area calculated. There was good inter-observer agreement: 58 SLBs were graded as Grade 0, 163 as Grade 1 and 27 as Grade 2. Of the 30% of the population with a Grade 2 score, all had abnormalities at the insertion and
Shutterstock/Sivolob Igor
Seen Even Without Clinical Signs
Ultrasonic evidence of subclinical abnormality of a suspensory ligament branch.
Image courtesy of the Equine Veterinary Journal
almost all these abnormalities were palmar-abaxial on the transverse images and abaxial/central-abaxial on the longitudinal images. There were significantly more Grade 2 lesions in the medial SLBs compared to lateral SLBs, possibly related to asymmetrical loading of the medial branches. The mean CSA of medial and lateral branches was between 1.3 and 1.4 cm2 but CSA was an insensitive indicator of subclinical injury. CSA was significantly larger in the medial SLBs than lateral SLBs. The researchers advised comparing CSA with the corresponding branch in the contralateral limb to identify unilateral enlargement. All abnormalities were classed as subclinical as no horse developed SLB injury in the season following scanning. Medial SLBs were more prone to Grade 2 lesions than lateral SLBs. None of these ultrasonographic ab-
normalities were associated with clinical injury. The mean cross-sectional area of the medial SLB was
larger than the lateral SLB, so they advised a comparison with the contralateral limb. MeV
For more information: Fairburn AJ, Busschers E, Barr ARS. Subclinical ultrasonographic abnormalities of the suspensory ligament branches in National Hunt racehorses. Equine Vet J. 2016 Nov. 9 ([Epub ahead of print]). http://onlinelibrary.wiley.com/doi/10.1111/evj.12639/full
New Applicator
Continued from page 3 The new applicator will be available beginning January 2017. For more information, contact your Merck sales representative or call 1-800-521-5767.
Click here to watch video
Flu Avert IN is a modified-live, intranasal equine influenza virus (EIV) vaccine that stimulates a broad immune response—similar to natural EIV infection—at the site of infection. The vaccine is shown to stimulate both local and systemic immunity, and escalate mucosal immunity that is both antigen (EIV) and non-antigen specific, potentially improving the horse’s defense against other respiratory pathogens that enter via the upper respiratory tract. Flu Avert IN is safe and effective with no risk of injection site reactions. Just one dose is required for primary immunization or as a booster to any other EIV vaccine, making it an ideal choice for naïve horses or horses with an unknown vaccination history. It is often recommended for high-risk horses—performance horses, horses in training, prior to shipping and horses moving from a low risk to high risk area. In unvaccinated horses or horses with an unknown vaccination history, an intranasal vaccine such as Flu Avert is recommended in the face of an EIV outbreak because of its rapid onset of immunity—just five to seven days in naïve horses following a single dose. MeV
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news notes
Equine PET Scanner Showing Success at UC Davis Veterinary Hospital After acquiring an equine positron emission tomography (PET), the University of California Davis veterinary hospital tested six horses to validate a clinical protocol. The horses were racehorses recently retired from the track or training on a treadmill at the California Animal Health and Food Safety Laboratory. Both PET and computed tomography (CT) scans were performed under the same anesthetic procedure. The anesthesia time remained under three hours with approximately 90 minutes for the PET scan and 30 minutes for the CT scan, which allowed imaging of up to six different areas. They were also imaged with magnetic resonance imaging (MRI) and scintigraphy. Stress remodeling lesions were documented, in particular in the fetlock and the carpus. Several of these lesions were not apparent on
scintigraphy, CT or MRI, confirming the advantages of PET imaging. The pattern of uptake observed on the PET images matched areas of known occurrence of lesions. In early October, a clinical trial was started in client-owned animals funded by the Grayson JockeyClub Research Foundation and UC Davisâ&#x20AC;&#x2122; Center for Equine Health. The trial enrolls horses with lameness, already imaged with either scintigraphy or MRI, but requiring additional information. Currently, four Warmblood horses have been imaged. The lesions identified included subchondral bone remodeling in the fetlock and the tarsus, remodeling of the navicular bone, focal active resorption of the coffin bone, osseous remodeling at the insertion of the suspensory ligament and remodeling of the canon bone. MeV
Figure 1
Figure 2
Figure 3
Figure 1: The new equine PET scanner arrived at the UC Davis veterinary hospital in August. Figure 2: Sagittal (A), dorsal (B) and transverse (C, D) fused PET/CT images of the right carpus of a 2-year-old Thoroughbred racehorse. There is marked increased radiopharmaceutical uptake at the distal medial aspect of the radial carpal bone and proximal medial aspect of the third carpal bone. Figure 3: Transverse PET (A), fused PET/CT (B) and CT (C) images through the right front proximal metacarpus of an 8-year-old Warmblood gelding. Local analgesia had identified pain in this area. The PET images demonstrate marked focal increased uptake at the palmar aspect of the third metacarpal bone at the lateral aspect of the origin of the suspensory ligament. The CT did not demonstrate significant abnormality in this area.
For more information: Spriet M, Espinosa P, Kyme AZ, et al. Positron emission tomography of the equine distal limb: exploratory study. Vet Radiol Ultrasound. 2016;57(6):630-638. http://onlinelibrary.wiley.com/doi/10.1111/vru.12430/abstract 12
Issue 12/2016 | ModernEquineVet.com
technician update
In plain sight: Corneal ulcer, other issues afflict Arabian mare A 19-year-old Arabian mare, weighing 420 kg, was admitted to the North Carolina Stateâ&#x20AC;&#x2122;s Veterinary Teaching Hospital (NCSU-VTH) and was evaluated by the Ophthalmology Service for an acute melting corneal ulcer in the right eye on Sept. 14, 2010. The owner had noticed a swelling in the ventral palpebra on Sept. 12 and called her regular veterinarian who came out that afternoon and diagnosed an infected ulcer. The mare was put on atropine drops, triple antibiotic drops and banamine. By that evening, the owner felt that the mareâ&#x20AC;&#x2122;s eye appeared diffusely milky. The mare also had a history of squamous cell carcinoma removed from her right eye in June 2010 and follow-up treatment with mitomycin. She had had a recent history of mild laminitis after eating too much hay, which the owner treated with phenylbutazone and limited feed. Upon arrival to the NCSU-VTH, a physical exam was completed by a fourth-year student, resident and a senior clinician. The initial physical examination showed that there were abnormal findings with the right eye. All other components of a physical examination were within normal limits. The left eye seemed comfortable with all other structures presented within normal limits. The left eye had mild blepharospasm, moderate conjunctival and sclera hyperemia, diffuse corneal edema and white cellular infiltrate, a 20 mm circular area of keratomalacia/melting ulcer in the axial cornea that takes up fluorescein stain, peripheral rim of white cellular infiltrate in the remainder of the cornea, deep furrow in ventrolateral ulcer, and the intraocular structures were unable to be assessed. A complete blood count (CBC) and chemistry were obtained and all values were within normal limits. A corneal cytology and culture were also obtained. The cytology revealed rod-shaped bacteria, an increased number of degenerate neutrophils and clumped epithelial cells. The culture revealed a heavy growth of Pseudomonas aeruginosa. The mare was placed in a stall and a subpalpebral lavage catheter was placed while clinicians reviewed their findings with the owner. The mare received medical management overnight including numerous eye medications, systemic antifungal, systemic
antibiotic, a proton pump inhibitor and pain management. She received voriconazole through lavage catheter every other hour, moxifloxacin through lavage catheter every other hour, autologous serum through lavage catheter every other hour, atropine through lavage catheter twice a day, omeprazole orally every 24 hours, flunixin orally every 12 hours, fluconazole orally every 24 hours, and trimethoprimsulfamethoxazole (TMP-SMX) orally every 12 hours. The melting corneal ulcer presented with a soft gelatinous appearance to the cornea, with a tan undulant surface and excess tissue dripping onto the ventral palpebra. Conjunctival, corneal and amnion grafts can all be used as surgical treatments. The choice depends on the
Courtesy of Ms. Hopkinson, NCS-VTH
By Heather R. Hopkinson, RVT VTS-EVN
Placement of amnion graft ModernEquineVet.com | Issue 12/2016
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Courtesy of Ms. Hopkinson, NCS-VTH
technician update
Perforation of right eye
severity and progression of the disease. In this case, the lesion was too large to ressect and replace with a corneal transplant. A conjunctival graft was not the best option either because the lesion was too large; the mare would essentially be blinded once the graft scarred over. An amnion graft from frozen fetal membranes was another option. The amnion tissue provides stem cells directly to the damaged tissue to increase healing. This tissue eventually breaks down and falls off after about four to seven days. One drawback to this procedure was that the lesion would not be able to be visualized while it was in place and could inhibit the medications from reaching the infected cornea. Enucleation was the only definitively curative treatment and was the final option if the infection could not be medically controlled. On the morning of Sept. 15, the mare was bright, alert and responsive. Her physical examination was within normal limits. The mareâ&#x20AC;&#x2122;s right eye showed little improvement and still seemed painful. The ophthalmology service decided to continue medical treatment for one more day to see if the eye improved. She was maintained on the same eye medications, systemic antifungal, proton pump inhibitor and pain medication though out the day and night. On the morning of Sept. 16, the mare was quiet, alert and responsive. Her physical examination was within normal limits. Due to the slight worsening in appearance of the cornea and fear of perforation, the decision was made to place an amnion graft. The mare was sedated with detomidine and the procedure was performed standing 14
Issue 12/2016 | ModernEquineVet.com
in the stocks. A retrobulbar block was performed with lidocaine and the cornea was lavaged with proparicaine occasionally throughout the procedure. Three layers of amnion were laid down on the surface of the cornea and each sutured in place with 7-0 Vicryl suture. The first layer was tacked into place with seven simple interrupted sutures and then a simple continuous pattern around the circumference. The second and third layers were from the same graft tissue folded over on itself. The edge of the second and third layers were stretched over the first and sutured in place with a simple continuous pattern. Some excess amnion tissue was trimmed off. The mare recovered well from the procedure and was walked back to her stall. All medications were continued throughout the night and she was placed on intravenous fluids. Her IV fluids were plain lactated Ringers at a rate of 2 L per hour for a total of 10 liters. On the morning of Sept. 17, the mare was quiet, alert and responsive. Her physical examination was within normal limits. The mareâ&#x20AC;&#x2122;s eye seemed really painful and she was unable to close her eye fully. The eye had potentially perforated, the amnion graft was still in place but bulging off the surface, and the globe was much softer than that of the left eye. The perforation of the right eye was confirmed by the senior clinician. The raging infection that was causing the corneal ulceration combined with the concurrent uveitis has gradually been breaking down the cornea. With the large area of ulceration and diseased cornea, the prognosis for fixing this eye was poor. The most effective and curative treatment in this
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technician update
case was enucleation. All topical eye medications and oral fluconazole were discontinued and the enucleation was scheduled for later in the day. The right eye was prepared in a sterile manner. The mare was anesthetized with triple drip (ketamine, guafenisin, and xylazine in 1 L of 5% dextrose) anesthesia and positioned in left lateral recumbency with the head stabilized with a slight tilt to expose the eye. A retrobulbar block was performed with bupivacaine, as well as a palpebral block with bupivicaine. The dorsal bulbar conjunctiva was grasped with Bishop Harmon forceps and transected with Stevens tenotomy scissors approximately 4 mm posterior to the limbus, dissecting beneath the conjunctiva and Tenon’s capsule to the sclera. This incision was continued 360° adjacent to the globe capsule. The extraocular muscle insertions and optic stalk were transected with equine-curved enucleation scissors and the globe was removed. Sterile gauze and epinephrine diluted in of BSS was placed in the orbit to assist with hemostasis. The eyelid margins were excised with Metzenbaum scissors. The conjunctiva, nictitating membrane and the medial caruncle were subsequently removed. The deep layer of periorbital tissue and the subcuticular layer were closed with separate simple continuous patterns using 3-0 Vicryl. The skin was apposed with simple interrupted and cruciate sutures using 3-0 Nylon. The mare had a rough and prolonged recovery but was eventually walked back to her stall. She was placed on plain lactated Ringers IV fluids at a rate of 2 L per hour throughout the rest of the night. On the morning of Sept. 18, the mare was bright, alert and responsive. Her physical examination was within normal limits. She seemed comfortable with all the sutures in place and minimal discharge. The mare did seem slightly stiff which may have been a result from her rough recovery from her enucleation surgery. She was continued on omeprazole orally every 24 hours, flunixin meglumine orally every 12 hours and oral TMP-SMX every 12 hours. Over the next couple of days the mare seemed bright and more comfortable. Her feed intake was increased in increments, and she was allowed to be hand walked with grazing. By the time she was discharged on Sept. 20, the mare was on full feed and seemed comfortable. She was sent home on the following medications at the same dosages as previously mentioned: TMP-SMX, flunixin meglumine paste and omeprazole. The owner was informed that the mare’s sutures needed to be removed in 14 days. On Sept. 23, the mare presented to the North Carolina State University Equine Emergency Service for lethargy, inappetance and possible endotoxemia. 16
Issue 12/2016 | ModernEquineVet.com
After returning home from her enucleation surgery the owner noticed that she was not herself. On Sept. 22, the owner noticed that the mare was looking distended. She was seen by the referring veterinarian who worked her up as a colic. All vitals were found to be with in normal limits and no net reflux was obtained when a nasogastric tube was placed. Nothing abnormal was felt on rectal palpation at that time. Upon arrival to the NCSU-VTH, a physical exam was completed by a fourth-year student, resident and a senior clinician. The mare’s abdomen appeared distended, and she was depressed and dehydrated. On presentation she had dark tacky mucous membranes with a capillary refill time of 3 seconds. Her pulse was 44 beats per minute and her respiratory rate was 16 breaths per minute. At this time a 14-gauge 5.25-inch over the needle IV catheter in the mare’s left jugular vein, and secured in place with suture (2-0 Ethilon on a straight needle). Upon ultrasonic evaluation, marked amount of free fluid was seen in the left ventral flank area with 4–5 inches of space seen between the spleen and body wall. An abdominocentesis was performed and the fluid collected appeared to be urine. Fluid analysis revealed a creatinine of 28.8 mg/ dL, while serum creatinine was 16.3 mg/dL. An Argyle 20-inch straight thoracic tube was placed to the right of midline. A Heimlich valve was attached and the free fluid was caught in a 10 L bucket below. A urinary catheter was also placed and hematuria was expelled from the bladder. To facilitate the movement of fluid, the Foley catheter was replaced with a nasogastric tube, which increased the flow rate of the fluid. The total amount of fluid extracted from her abdomen and bladder was about 84 L. During fluid removal, the heart rate was monitored for rate and rhythm. After partial bladder evacuation, a scope was passed into her urethra to the bladder and a rent was seen ventrally at the apex of the bladder. The site was difficult to assess due to inadequate distension of the bladder. Both ureters were expelling urine into the trigone of the bladder normally. The mare was moved from the stocks and placed in a stall. She was given IV banamine, enrofloxacin and potassium penicillin. Hay, pellets and water were offered. She was disinterested in the food but drank some water. Food was to be pulled at 4 am with possible surgical correction of the rent occurring the following afternoon. Presenting CBC, chemistry and venous blood gas were: packed cell volume (53%), protein (8.7 g/dL), fribinogen (600 mg/dL), hyperkalemia (6.2 mmol/L), hyperglycemia (245 mg/dL) and azotemia (BUN [143 mg/dL], creatinine [16.3 mg/dL]). The creatinine kinase was too high to register but with dilution; it was 1,812 units/L,
Teaching Points This case had many components of nursing skills. For all cases admitted to the NCSU- VTH, baseline vital signs and a history are obtained. Beyond those basics, each case is treated individually and is dependent on clinician discretion. All patients that are admitted to the NCSUCVM receive a physical examination and are assigned a pain score at least twice a day. This mare was a unique and interesting case because she was in the hospital twice within three days for two completely different problems. For this case, I performed multiple physical examinations and monitored not only her eye but also for signs of colic, since general anesthesia in ophthalmology patients tends to induce cecal impactions when they are not hydrated. This is also why we walk and graze our ophthalmology patients. I also monitored her IV fluids using a gravity dial administration, administered eye medications through the lavage catheter, administered oral medications, and administered intravenous medications through the IV catheter. When this mare came back to the hospital for her ruptured bladder, I also monitored her urinary output and pain very closely. It was also important to monitor her incision since she did lay down a lot due to her laminitis.
Shutterstock/nelelena
and the venous blood gas was within normal limits. The clinicians elected to take the mare to surgery to repair the ruptured bladder the next day. The mare was sedated IV xylazine and then induced with midazolam and IV ketamine. She was then placed in dorsal recumbency. A 20 cm midline incision was made 5 cm caudal to the umbilicus and extended to the teats. The subcutaneous tissue and abdominal muscles were incised down to the linea alba. The linea alba was incised and upon entry into the abdomen, more than 25 L of red-tinged fluid was expelled and suction was applied. After partial evacuation of the peritoneal space, the bladder was located. The ventral aspect of the bladder was grasped and elevated for evaluation. A focal area of necrotic and fibrinous tissue was seen on the serosal surface at the apex. A 4 centimeter rent was located within the tissue and the cranial aspect of the opening was incised. The edges of the rent were freshened and then apposed with a simple continuous using 2-0 Vicryl. An inverting pattern (Lembert) was applied over the simple continuous using 2-0 Vicryl. The bladder was replaced into the abdomen and the peritoneal space was suctioned. The linea alba was closed with a simple continuous pattern using No. 3 Vicryl. The subcutaneous layer was closed using a simple continuous pattern and 2-0 Vicryl, with occasional tacking to the linea alba to decrease dead space. The intradermal closure was a subarticular pattern with 2-0 Vicryl. Stainless steel staples were placed along the incision. A urinary catheter was placed and recovery was slow but uneventful. The mare was slightly ataxic afterward. The following morning the mare was quiet, alert, responsive. She did not have any appetite overnight but did eat a fair amount of grass when taken outside. Post operatively she urinated a fair amount the entire night. Her ventral abdominal drain was pulled, after ultrasonography revealed only a small amount of fluid within the abdominal cavity. After the drain was pulled out, approximately one-half liter of serosanginous fluid came out of the drain incision site. A bandage was applied to the area to help soak up the residual amount of fluid left in the abdomen. She was continued on the previous medications but omeprazole was added to her regimen. She had been on IV fluids (lactated Ringers solution) at 2 L an hour. The mare also had ice boots placed on all four limbs to prevent laminitis. Over the next several days, the mareâ&#x20AC;&#x2122;s blood work continued to improve and her incision was healing well. Her appetite continued to increase. On the morning of Sept. 28, the mare seemed a little reluctant to move and had increased digital pulses in the front limbs only. Radiographs showed that there was
severe palmer rotation of the distal phalanges with a very thin sole at the distal margins and rotation of P3 which was more severe on the left forelimb. At this time corrective shoeing was placed. Over the next few weeks the mare continued to improve. Her blood work had returned to normal before discharge. She had been weaned from most of her medications and upon discharge she was on oral enrofloxacin and phenylbutazone. The mare was discharged on Oct. 9. MeV
About the author
Heather, who is an equine veterinary technician at the North Carolina State University College of Veterinary Medicine, received her VTS in Equine Veterinary Nursing in 2011 and is the current president of the Academy of Equine Veterinary Nursing Technicians. She is also the current vice president of the North Carolina Association of Veterinary Technicians. ModernEquineVet.com | Issue 12/2016
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