Checking for Equine Gastric Ulcers

Here’s what to expect if your horse needs to undergo gastroscopy, the only surefire way to check for equine gastric ulcers.
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equine gastric ulcers
Gastroscopy is the only surefire way to check for equine gastric ulcers. | Photo: Courtesy Danny Holbrook

April Knudson, DVM, holds a doctor of veterinary medicine from the University of California, Davis. Here, she answers a question about what to expect if your horse needs to undergo gastroscopy to check for equine gastric ulcers.

Q.My veterinarian thinks my horse has equine gastric ulcers and has suggested I bring him in for a gastroscopic examination. What is it, what can I expect to happen, and how should I prepare my horse?

A.If your veterinarian has recommended a gastroscopy, sometimes called a “stomach scoping,” he or she probably thinks your horse has equine gastric ulcers. About 62% of horses have them to some degree. The good news is they can be treated and prevented in the future.

While stomach ulcers can be presumptively diagnosed (by ruling out other possible problems and watching a horse’s response to treatment) without performing a gastroscopy, if your veterinarian has recommended this procedure he or she has reason to want to make a definitive diagnosis in order to proceed with treatment. Gastroscopy is the only surefire way to know what the inside of your horse’s stomach looks like. Here’s how to be sure you get the most accurate results and what to expect during the examination.

For the best results, I typically gastroscopy be conducted as early in the morning as possible because the horse cannot eat anything for 12 hours prior to the exam and should not drink water for four to six hours prior. What seems to work for most horse owners is to feed a light evening meal, and ensure all the scraps are cleaned up 12 hours before appointment time. If the appointment time is 10 a.m. the next day, the hay/feed needs to be completely gone by 10 p.m. the night before, and the water needs to be removed or turned off at 6 a.m. the day of the exam.

Avoid removing hay/feed and water at the same time. Your horse should have access to water for several hours after removing hay/feed, to help the already eaten hay move out of the stomach. Your horse should not have access to grazing pasture for 12 hours before the exam. Also, make sure your horse isn’t grazing on anything else such as shavings, straw, shrubs, trees, or scraps of grass under a fence. You might need to strip the stall or put a grazing muzzle on your horse if he or she is eating the bedding.

Also, avoid use hay, grain, or other types of treats to entice your horse onto the trailer or into the area you have set aside for the veterinarian if he or she is performing the exam on your property—remember, your horse’s stomach must be empty during the exam. Even the smallest amount of feed (or treats) can ruin your chances for an accurate examination.

To start, your veterinarian will likely perform a check of your horse’s vital signs and administer a light, short-acting sedative. Then the endoscope will be passed through the horse’s nose, to the pharynx, where the horse swallows the scope and your veterinarian pushes it down the esophagus to the stomach.

The veterinarian will be trying to see several parts of the stomach, including the pylorus (exit to the small intestine), duodenum (first part of small intestine), glandular mucosa, squamous mucosa, margo plicatus, and cardia (where the esophagus meets the stomach). During the procedure, he or she will be checking for anything abnormal, such as ulcerations, erosions, reddening, thickening, normal or abnormal coloring, and parasites, especially bot larvae.

If identified, ulcers are commonly (although not always) graded by a numeric system, an example of which is as follows:

  • Grade 1—Mild ulcers with small lesions or damaged tissue
  • Grade 2—Moderate ulcers with large lesions
  • Grade 3—Extensive lesions with deep ulceration and bleeding

If your horse is diagnosed with ulcers, a course of treatment with omeprazole (marketed in a U.S. Food and Drug Administration -approved formulation as GastroGard) could prove beneficial. Following treatment, it is possible for ulcers to return, particularly during times of stress. To prevent their reoccurrence, consider administering omeprazole (under the FDA-approved formulation UlcerGard) during times of stress.


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