What if your horse could swallow a tiny capsule containing a camera, giving you and your veterinarian a look at the nearly 100 feet of twisting, turning intestinal tract, and any gastrointestinal issues therein? This isn’t futuristic musing—one veterinarian has determined that the approach, called wireless capsule endoscopy, is a workable way to check the gastrointestinal mucosa (lining) for ulcers and injury, though maybe for just the first 80-or-so feet.
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 Alberta, Canada, wanted to be able to see “intraluminal” lesions within the small and large intestines. These are likely quite common but challenging to diagnose with current imaging techniques. So, taking a page from human and small animal medicine, he recently tested the new imaging technique in horses, presenting his findings at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.
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—only reaching just past the stomach to the first section of the small intestine–capsule endoscopy is completely wireless, with the capsule able to travel the length of the tract, recording video as long as its battery permits.
While physicians have used capsule endoscopy technology in human gastroenterology for more than a decade, it’s only recently become commercially available on the veterinary market for dogs (as ALICAM), said Leguillette, and shows promise for use in horses.
“The principle of this system is to have the camera move into the GI tract lumen (cavity) and record videos of the intestinal mucosa (lining) while the horse is fully ambulatory and engaged in regular activities,” he said. “The camera is then collected from the manure.”
How it Works
Leguillette reviewed his method for using capsule endoscopy in horses successfully. In preparation for capsule administration, he 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.
“The preparation of the patient is important,” Leguillette said. “If feed is not withdrawn for long enough, feed material can obstruct good visualization of the mucosa. However, if feed is withdrawn for too long, motility is decreased too much for a good examination.”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 for best results.
One of the challenges with this technique, he said, is that it can take anywhere from two to 14 days for the capsule to pass through the horse in his 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 if it wasn’t immediately visible.
After they’ve collected the capsule, veterinarians can ship it to the manufacturer for video download and interpretation. They then receive a report detailing lesion findings and images.
Leguillette has performed more than 20 capsule endoscopy examinations on adult horses, weanlings, and a Miniature Donkey. In his experience he’s determined that:
- The camera records at least 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 runs out;
- The camera provided good images of the stomach’s glandular (lower) and pyloric (the opening from the stomach into the small intestine) regions, the small intestine mucosa, and the ileocecal junction (the 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 (bleeding just beneath the lining surface), polyps, sand accumulation, and parasites.
“The capsule camera allowed diagnosing intestinal lesions that would have been otherwise missed,” he said, adding it’s also indicated for chronic colic cases or suspected intestinal tumors.
While the technique’s advantages include clear assessment of the small intestine mucosa, ease of use on the farm, and cost effectiveness (the entire procedure costs around $400 and doesn’t require investing 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.
“In summary, the capsule technique is safe to use in equids of all sizes,” he said. “It provides excellent detailed visualization of the pyloric area of the stomach, of the small intestinal mucosa, and of the ileocecal junction.”