The Horse

MAR 2019

The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.

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YOUR GUIDE TO THE 2018 AAEP CONVENTION A38 March 2019 The Horse | AAEP Wrap-Up TheHorse.com/AAEP2018 ■ 10 healthy controls. Control horses had plasma levels of 165 IU/L and peritoneal fluid CK levels of 6 IU/L; horses without strangulating lesions had plasma CK levels of 271 IU/L and peritoneal levels of 6 IU/L. Horses with strangulating obstructions had signifi- cantly higher values: plasma CK values were 1,181 IU/L and peritoneal 185 IU/L. Kilcoyne said peritoneal CK levels are more likely to correctly identify horses with strangulating obstructions (sensitiv- ity of 95.5% and specificity of 82.1%, with a cutoff of 16 IU/L) than peritoneal fluid lactate levels (sensitivity of 81.8%, speci- ficity of 92.1% at a 3.7 mmol/L cutoff)— another biomarker vets frequently use to predict ischemia. However, CK poses a slightly higher risk of yielding false posi- tives than lactate, she added. She suggested veterinarians measure both peritoneal CK and lactate levels in colicking horses, always factoring in the horse's clinical signs when interpreting the findings. She said the development of a stall-side CK test could expedite diagno- sis in both field and hospital settings. There's a New Way to View Horses' Intestinal Lining What if your horse could swallow a tiny camera, providing a look at the nearly 100 feet of twisting intestinal tract and any issues therein? This isn't futuristic musing—one vet has determined that the approach, called wireless capsule endos- copy, is a workable way to check much of the GI mucosa for ulcers and injury. Renaud Leguillette, DVM, Msc, PhD, Dipl. ACVIM, ACVSMR, professor of equine internal medicine in the University of Calgary's Department of Veterinary Clinical and Diagnostic Science, in Al- berta, Canada, wanted to be able to view "intraluminal" lesions within the small and large intestines. These are common but challenging to diagnose with current imaging techniques. So, taking a page from human and small animal medicine, he tested capsule endoscopy in horses. In contrast to traditional endoscopy, which involves passing a 3-meter-long scope (a little less than 10 feet) through the horse's nostril into the GI tract, capsule endoscopy is wireless, with the capsule able to travel the length of the tract, recording video as it goes. While physicians have used capsule endoscopy technology in human gastro- enterology for more than a decade, it's only recently become commercially avail- able on the veterinary market for dogs (as ALICAM), said Leguillette. "The principle of this system is to have the camera move into the GI tract lumen (cavity) and record videos of the intestinal mucosa while the horse is … engaged in regular activities," he said. "The camera is then collected from the manure." How it Works In preparation for cap- sule administration, Leguillette said, keep the horse stalled and withhold his feed for 24 hours. Hand-walk him at least twice during this period, and withhold water for the last 12 hours. "If feed is not withdrawn for long enough, feed material can obstruct good visualization of the mucosa," Leguillette said. "However, if feed is withdrawn for too long, motility is decreased too much for a good examination." After administering the capsule via nasogastric tube, reintroduce water and feed at three and 12 hours, respectively, he said. Leguillette recommended feeding the horse hay only, four times a day, and keeping him in a stall or small pen. One of the challenges with this technique, he said, is it can take two to 14 days for the capsule to pass in the horse's manure. This requires the owner or barn staff to collect all manure and store it (e.g., in large plastic bins) for inspection. Leguillette said he used radiography (X rays) to detect the capsule in these bins. Then veterinarians can ship the capsule to the manufacturer for video download and interpretation. They receive a report detailing lesion findings and images. Study Results Leguillette has performed more than 20 capsule endoscopy exami- nations on adult horses, weanlings, and a Miniature Donkey. He's determined that: ■ The camera records >35,000 frames; ■ It spends about four hours recording in the stomach, two to five hours in the small intestine, and about 10 hours in the cecum before its battery life ends; ■ It provided good images of the stom- ach's glandular (lower) and pyloric (the opening from the stomach into the small intestine) regions, the small intes- tine mucosa, and the ileocecal junction (of the small intestine and cecum at the start of the large intestine) mucosa; and ■ Visualization of the cecal and colon mucosa was poor. Using this technique, Leguillette has identified gastric ulcerations, erosions, submucosal hemorrhage, polyps, sand accumulation, and parasites. "The capsule camera allowed diagnos- ing intestinal lesions that would have been otherwise missed," he said, adding it's also useful for chronic colic cases or suspected intestinal tumors. While the technique's advantages in- clude clear assessment of the small intes- tine mucosa, ease of use on the farm, and cost effectiveness (the entire procedure costs around $400 and doesn't require in- vesting in special equipment), Leguillette said its downsides are its recovery time in manure, the extra on-farm management, and its inability to visualize the cecal and large intestine mucosa. Finally, the capsule technique is safe to use in equids of all sizes, he said. h COURTESY DR. RENAUD LEGUILLETTE Capsule endoscopy shows promise for helping vets diagnose intestinal lesions in horses. ONLINE extras Visit TheHorse.com/AAEP2018 ■ Veterinarians Discuss How to Manage Equine Gastric Ulcers, TheHorse.com/166040 The capsule camera allowed diagnosing intestinal lesions that would have been oth- erwise missed." DR. RENAUD LEGUILLETTE

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