The Ulcer Dilemma

Thanks to new medicine and new management techniques, ulcers in horses can not only be treated, but prevented in the first place.

Ulcers are a common scourge in horses. Gastric ulcers affect up to 93 percent of racehorses, about 60 percent of horses in other performance careers, and up to 59 percent of foals—particularly in foals raised in confinement. Colonic ulcers are only slightly less common, also affecting actively used horses.

Unfortunately, ulcers are hard to detect because subtle symptoms may go unnoticed; they weren’t even recognized in horses until just over 30 years ago. The gastric ulcer findings noted above, based on research by Dr. Michael J. Murray and his associates, were published in Equine Veterinary Journal in 1989 and 1996. An even more recent study in 2005, by Dr. Frank Pellegrini, DVM, has shown that colonic ulcers affect perhaps 60 percent of performance horses.

Fortunately, ulcers can be treated once they are diagnosed, and affected horses can continue their careers with little interruption.


In adult horses, the most typical signs include poor performance, poor appetite, and mild abdominal pain or colic. A horse with ulcers may lose weight, have a poor coat, a tucked-up appearance at the flank, and a change in attitude. He doesn’t feel good and this affects his manner.

Signs of ulcers in foals include intermittent colic or diarrhea, rough hair coat, poor growth, or drooling. Discomfort may be shown by grinding the teeth, lying on the back to try to ease abdominal pain, or interrupted nursing. The foal may nurse vigorously for a moment and then halt abruptly, due to pain in the stomach.


Stress is the leading cause of equine ulcers. The lifestyle of many horses, which includes confinement, high level competition, high energy diets rather than pasture, contributes to stress (and ulcers). So does any significant change in the horse’s routine or life style, such as confinement with little or no turnout or grazing, trailering, training, lay-up due to sickness or injury, changes in herd dynamics in a group of horses, etc.

“These horses are confined and worked hard,” says Dr. Gary White of Salisaw Equine Clinic, Salisaw, Okla. “I’m not sure whether it’s the confinement itself or just the stress related to the confinement that makes the horse vulnerable.”

In addition, he notes, “We feed our hard-working horses large amounts once or twice a day and load them up with a high energy diet. Some people feel this may contribute to ulcer development.

“Horses turned out on pasture are usually ulcer-free. They lead a more natural life and can eat whenever they want.”

To understand how a feed program can contribute to ulcers, consider how the horse’s digestive system works. Food stays in the stomach, which is relatively small, for only a short time—perhaps 30 minutes—before passing to the small intestine. Protein, grains, and fat are digested here. After perhaps one to three hours, food passes to the hindgut, and especially the colon, which break down plant fibers. This process is done by the fermentation action of bacteria, the gut microflora. This produces volatile fatty acids, which supply the majority of the horse’s energy and sustenance.

What this means is that horses are not designed to process large amounts of carbohydrates. Grain rations above seven pounds a day are not, in many cases, completely digested in the stomach and small intestine. Leftover carbs pass on to the hindgut, where they can lead to lactic acid and hindgut acidosis. In this environment the good bacteria die off, while bad bacteria flourish and can lead to colonic ulcers and colic.

Strenuous exercise may also be a factor in gastric ulcers. The top portion of the stomach is not as well protected from acid because it has less mucus-producing glands. Most stomach ulcers occur in this portion of the lining. At fast gaits and more intense physical effort, acidic contents are forced higher in the stomach. The longer and more intense the exercise, the more damage can be done to the stomach lining.


Usual diagnosis for gastric ulcers is by scoping, looking at the lining of the stomach with a long endoscope. Not all ulcers in adult horses can be detected with an endoscope, however, since it won’t reach below the top part of the stomach. Some horses have ulcers farther down. In one study, Dr. Murray found that 58 percent of horses in which the deeper portions of the stomach were checked had ulcers. Many of these did not have ulcers in the top portion, so their deeper ulcers would generally be undetected in a typical examination.

To help veterinarians identify horses that should have endoscopic examinations and treatment, Dr. Rick Mitchell from Fairfield Equine Associates, Newtown, Conn., studied ulcers in 134 sport horses and presented his findings in 2001. Horses found to have ulcers were treated for 28 days with Gastrogard (a brand of omeprazole, available only by prescription). Most improved and required no further treatment. A few continued to have ulcers on follow-up exams until significant changes were made in their training, feeding and competition schedules to reduce stress levels. In most horses, a lower dose of omeprazole was adequate for maintenance therapy after healing.

Even though less expensive products are often used in an attempt to prevent or treat ulcers, omeprazole is still the only prescription medication approved by the FDA for horses. It’s available as Gastrogard and a second branded form, Ulcergard. This last form is another brand name omeprazole medication, packaged to make it more useful and easier to administer. It is a non-prescription drug, but is available only through veterinarians. The dosing mechanism for Ulcergard allows you to treat a horse with active ulcers, giving the whole tube, or use it as a preventive—giving just a quarter tube per day to the average 1,200-pound horse. This dosage is an effective preventive level, according to information presented by Dr. White at the 2003 meeting of the AAEP.

“I’ve actually done two trials on this, using Ulcergard,” says White. In one, he adds, “we looked at horses that were just beginning in race training.” These were young horses just starting into a stressful period of their lives, and vulnerable to ulcers. The second trial looked at an eight-day dose for prevention, which also proved beneficial.

In the trial, some horses were given a low “preventive”?dose, and others, a placebo. “We found most of the horses that were on the low dose of omeprazole did not have ulcers, and most of the horses that were on the placebo paste did have ulcers. In the placebo treated group, 35 of 39 horses had developed ulcers. In the low dose group, 31 of 38 horses had no ulcers,” says White.

In the second study (results published in June, 2007, in JAVMA) 102 horses with normal gastric linings were divided into groups at four trial locations. Some received no dose and others were treated with a paste formulation of omeprazole daily (1/4 the dosage for treating active ulcers) for eight days. Training regimes varied among locations and included early training for western performance events and race training. In the omeprazole-treated groups, 88 percent of the horses were still free of gastric ulcers, vs. only 27 percent of the untreated horses. These results showed that horses in light to heavy training for as short as eight days were at risk for ulcers, and that administering omeprazole at preventive levels decreased the incidence of developing ulcers.

Mitchell agrees with the findings, and says that omeprazole is much better than any antacid or coating agent. “But one product that contains a combination of antacid and sulcralfate can be a good adjuvant to Ulcergard in helping prevent ulcers. Sucralfate turns into a gel-like substance in the presence of acid and adheres to tissues. We justify its use in our practice as a short-term protectant—administered to horses just before exercise. This gives a buffering effect against acids during exercise,” says Mitchell. But this product is only helpful to protect the stomach lining from the effects of one exercise episode.

We should note that generic omeprazole is also available, and is a lower-cost option. However, its use is not yet widely understood among veterinarians, and it must be compounded properly by a pharmacist to buffer it and ensure it gets delivered to the small intestine.


How can you deal with colonic ulcers? Aside from pasture turnout—which is an effective antidote for all forms of ulcers—one good step to treat colonic ulcers is to reduce the amount of grain in the diet, and to feed grains such as oats, which are 50 percent fibrous hull and are less carbohydrate-rich. You can also substitute fats for some calories, or increase the amount of fiber in the diet, such as soaked beet pulp, chaff, and the like. Your vet can advise you on your best options.

A digestive supplement such as Succeed, from Freedom Health, is another option. According to company founder John Hall, Succeed helps the horse rebalance the bacterial flora in the hindgut. Succeed contains a blend of oat oil and oat flour, irradiated yeast, and enzymes that can help mitigate the effects of the typical stall feeding schedule, he says. A month’s supply runs about $100.






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