racehorsemeds.comThe majority of performance horses have gastric ulcers (also known as peptic ulcers) about two-thirds of those horses also have colonic ulcers. There are many reasons for this. Let’s begin with the fact that they are grazers and they are constantly producing bile. We put them in a stall, which is an unnatural environment (because they are herd animals), which causes stress plus we control their feeding causing gaps in their eating while their gut is constantly churning bile. If they are performance horses, the stress level increases. Some horses are stressed every time their environment changes. Most horsemen believe that it is always because of the new environment. Sometimes it is as simple as that. Most of the time it is the stress of that change or the uncertainty of where they are that causes stress which increases the production of bile and either ignites an ulcer or aggravates existing ulcers which causes a lack of appetite, weight loss, poor coat and possibly much more.

In adult horses, gastric ulcers occur more frequently in horses that perform athletic activities… with the highest frequency found in thoroughbred racehorses (80-90%), followed by endurance horses (70%), then show horses (60%). Researchers have found that exercise increases gastric acid production and decreases blood flow to the gastrointestinal (GI) tract.

In addition to when horses exercise, the acidic fluid in the stomach splashes and do expose the upper and more vulnerable portion of the stomach (squamous mucosa) to an acidic pH.

Why are gastric ulcers so common in horses?

First of all, the stomach of the horse is smaller as compared with the stomach of other species. Because of this, horses cannot handle large amounts of food.  They are built to graze and eat frequent, small portions of feed for extended periods of time.

In a natural grazing situation, the horse requires a steady flow of acid for their digestion.  Therefore, a horse’s stomach produces acid 24 hours a day, 7 days a week… up to 9 gallons of acidic fluid per day, even when not eating! In a natural, high-roughage diet, the acid is buffered by both the steady flow of feed and saliva.

Secondly, by understanding the horse’s anatomy, it is possible to see how ulcers could be considered a “man-made” disease. When horses are fed two times per day, the stomach is subjected to a long, extended period without feed to neutralize the acid. Furthermore, high-grain diets produce volatile fatty acids that can and will also contribute to the development of ulcers.

Other risk factors for developing gastric ulcers include their physical and environmental stress such as transportation stress along with stall confinement (intermittent feeding and lack of exposure to other horses). Recent studies have demonstrated that aa much as a few hours of transportation can induce gastric ulceration in horses that had none prior to departure, as determined by gastroscopy.

Finally, chronic administration of some non-steroidal anti-inflammatory drugs (NSAIDs) (such as phenylbutazone, flunixin meglumine or ketoprofen) can decrease the production of the stomach’s protective mucus layer, making it more susceptible to ulcers.

There are simple treatments for horse ulcers:

  • Feed horses frequently or on a free-choice basis (pasture). This helps to buffer the acid in the stomach and stimulate saliva production, nature’s best antacid.
  • Reduce the amount of grain and concentrates and/or add alfalfa hay to the diet. Discuss any feed changes with your veterinarian so that medical conditions can be considered.
  • Avoid or decrease the use of anti-inflammatory drugs. If anti-inflammatory drugs must be given, consider newer ones such as firocoxib, if appropriate.
  • Limit stressful situations such as intense training and frequent transporting.
  • If horses must be stalled, allow them to see and socialize with other horses (or out an acrylic mirror in their stall) as well as have access to forage.


For gastric ulcers it is thirty days of OMEPRAZOLE (a full 10ml tube of 2.28 grams), then drop the dosage by half for thirty days and then a maintenance dose of 1/4 tube.  If you see any type of negative difference in your horse’s behavior, then a full will be needed as a maintenance dose.  For colonic ulcers, a daily dose of 1.4mg of MISOPROSTOL will treat that issue.  It is the one-two punch that almost every performance horse needs.    You will see a difference in appetite, weight gain, coat and overall better health and performance in 2-4 weeks.