Equine gastric ulcer syndrome (EGUS) is increasingly being recognized as a major health problem affecting all equine athletes, including endurance horses. Research has shown that 90% of racehorses and almost 60% of all performance horses are affected by EGUS.

Although EGUS was initially believed to be a health concern primarily affecting racehorses, further studies have confirmed that ulcers affect horses in many other competitive disciplines including eventing, dressage and show jumping.

Extensive studies have been done in many disciplines but not endurance. Several investigators have looked at endurance horses but not in large numbers. Endurance horses do not gather in large numbers except at rides which is a poor place to perform endoscopy due to the necessity to fast and the advantages of sedation.

In the spring of 2003, the Pride Project, a private research entity, with the help of some dedicated AERC members, conducted a study of the incidence of equine gastric ulcer syndrome in endurance horses. As of April 30, 2003, 140 active endurance horses were "scoped" at 15 clinics in eight states and 50% of them had ulcers. Lack of time and finances have prevented any further studies.

Ulcers are the result of excess gastric acid damaging the stomach lining. Unlike the human stomach, which generally produces gastric acid only during meals, the equine stomach secretes acid continuously. Studies have shown that a mature horse will produce approximately 1.5 liters of gastric acid per hour. Consequently, when there is no food in the horse's stomach to act as a buffer against acidity, excess acid can eat through the protective lining and cause the formation of ulcers.

Studies published recently by Dr. Al Merritt at the University of Florida demonstrated that when a horse exercises at a trot or gallop, the unprotected part of the stomach is exposed to acid contents, causing ulcer formation.

Signs and symptoms of ulcers

There are many clinical signs and symptoms associated with EGUS; however, it is important to note that many horses with stomach ulcers do not exhibit any obvious signs. Because the prevalence of stomach ulcers in horses has only been recently understood, ulcer symptoms can go unrecognized by trainers, owners and veterinarians. What complicates the issue is that some horses with severe ulcers may not show any outward signs of illness, while others suffering from mild ulcers may behave very abnormally.

In adult horses, common signs include poor performance, colic, back soreness, attitude changes, resistance to training and poor appetite. Other signs associated with ulcers include poor body condition, a tucked-up appearance, and a poor coat.

Unfortunately, common clinical signs of ulcers are often overlooked or not observed until the problem has progressed. Because of this, stomach ulcers are often undiagnosed or misdiagnosed. While definitive diagnosis can only be made with endoscopy, the clinical signs and symptoms may form the basis for empirical therapy for ulcers after other disorders have been excluded.

Work is being done by Dr. Noah Cohen at Texas A&M School of Veterinary Medicine (and by others) on a blood test--originally urine but blood appears to be best--for sucrose levels that shows promise as an alternative diagnostic procedure. When I recently spoke with Dr. Cohen he told me that the test is more than a year away and needs much more testing before it will have widespread clinical benefits. Rumors are flying and excitement is premature. Here is how the test works: Sucrose is a very large molecule that is not absorbed in the normal horse stomach and shows up in the blood and urine of horses with ulcerated stomachs. The urine test is used in humans and dogs in some cases.

What causes ulcer formation?

There are several factors that predispose a horse to EGUS. A grain-heavy diet and infrequent grazing or reduced hay intake can lead to stomach ulcers within hours to days. Performance horses often go without feed several hours of each day during training, permitting acid build-up within the stomach and causing damage to the stomach lining.

Prolonged stabling or time spent in stalls, coupled with limited turn-out, can also contribute to ulcers. Extended periods of inactivity or strict confinement results in delayed emptying of stomach contents, conditions that are favorable to ulcer development.

On the opposite end of the spectrum, intense exercise or rigorous training actually increases acid production in the horse's stomach and reduces blood flow to the stomach. Consequently, strenuous exercise can be just as likely to result in stomach ulcers as inactivity.

Other factors such as shipping, frequent competition, unfamiliar surroundings and the use of analgesic anti-inflammatories, such as phenylbutazone and flunixin meglumine, have also been shown to contribute to equine stomach ulcers.

Where to start?

Confirming or ruling out EGUS in your horse is where you start. Endoscopes long enough to adequately examine a horse's stomach are few and far between. Universities have them and some of the more progressive equine practices do also. If your veterinarian does not have one you can be referred to a veterinarian who does. If your horse does have ulcers then the only course of action is to remove the source of stress (i.e., training, competition, etc.) until treatment is completed and then embark on rigorous preventive measures before resuming and continue during training and competition.

Ulcer treatment options

Very best: Gastrogard(R) - low volume palatable paste given once daily (uninterrupted) for 28 days. Advantages: FDA approved, low volume, very palatable and stable; 95% of horses treated for 28 days get well. Disadvantage: very expensive.

Good: Ranitidine (Zantax(R)) - a human ulcer drug. Dose for an average horse is nine tabs every eight hours for 28 days. Advantage: Cheap; you can treat an average horse for about $150. Disadvantages: Must be given every eight hours around the clock. Tablets need to be crushed and mixed with something. This drug has not been researched in the horse and does not completely clear up ulcers.

Poor: Cimetidine (Tagamet(R)) - another human anti-ulcer drug. To do any good you need to give 25mg/Kg every six hours for 28 days. Cheap but not very good and requires very frequent dosing.

Not effective: Sucralfate (Kerafate(R)) - this is another common human drug that is a coating agent and works primarily in the small intestines. Horses rarely have duodenal ulcers, therefore this drug is not considered a drug for treating EGUS. It has been reported to me that horses using Kerafate during competition seem to do better than when they do not get it.

Over-the-counter anti-ulcer products: I do not recommend any of the so-called anti-ulcer formulas sold over the counter for treatment. They are only acid reducers or soothing agents and will not treat ulcers. Some of these products, however, are useful in preventing EGUS.

Ulcer treatment and prevention

Good management and excellent nutrition (roughage in the stomach most of the time) plus anti-acid medications during periods of stress are the keys to ulcer prevention. Horses with gastric ulcers should not be subjected to the extreme stress of endurance. Medications which treat and prevent ulcers include:

Gastrogard(R) (Omeprazole). Gastrogard(R) is a drug that stops the production of acid in the stomach. It is an excellent treatment for equine gastric ulcer syndrome (EGUS). Severe cases of EGUS require 28 days of therapy. Some cases can be brought under control in 14 days. This drug will show up on drug testing and therefore is illegal to use associated with AERC endurance events. Gastrogard(R) clears the bloodstream quickly and it is believed that 36- to 48-hour withholding will result in a negative drug test for those using it as a preventive. As for horses being treated, interruption of therapy is not a good practice. Besides, competing a horse with ulcers is not a wise thing to do.

Treatment: Dose syringes will treat 1250 lbs. a day. The average endurance horse weighs 800 to 900 lbs. Ten tubes should treat for 14 days, and 20 tubes should last 28 days. Prevention: A preventive dose can be as low as one-fourth of the treatment dose. One syringe will cover 5000 lbs. per day. Figure your dose at your horse's weight divided by four. Remember you must withhold Gastrogard(R) at least 36 hours prior to an AERC event.

Neigh Lox(R) (Maalox for horses). This is just an anti-acid used to neutralize stomach acid. The label says it aids in the reduction of excess stomach acid. Use daily or just during stress of trailering and the actual event. A 3.5 lb. container will last 30 days and 25 lbs. will last six or more months.

Over-the-counter ulcer medications. There are several products that claim to be treatment for ulcers. They are primarily coating agents that at best may be useful for temporary pain relief or possibly useful after the ulcers have been cured as part of your prevention program.

Kerafate. Kerafate is an ulcer coating drug that works to shield the ulcer from additional irritation. It probably works best in the small bowel but seems to help in very mild cases. Kerafate may have little value in prevention even though it is widely used during competition as it apparently does not test.