Although not a new problem, stomach (gastric) ulcers are a condition that has recently received a lot of publicity, both in our professional journals and in lay publications and magazines. Surprisingly, it has been estimated that up to 50% of all foals will have gastric ulcers and that all horses will have some degree of gastric ulceration at sometime in their life. In one study it was found that 82% of racing Thoroughbreds had stomach ulcers. While these numbers are obviously high, not all horses will show clinical signs of gastric ulceration and in fact most will heal themselves without ever causing the horse an obvious problem. There is a very wide spectrum of severity of these ulcerations from essentially non-significant to life threatening. Various treatments are now available for addressing this condition.
The stomach of the horse is essentially separated into 2 regions covered by different cell types. The upper area is called the non-glandular or Squamous region, while the lower portion is known as the glandular portion of the stomach. The glands lining this lower portion secrete pepsin, an enzyme, and hydrochloric acid, both of which are responsible for the breakdown of undigested feed. Additionally these glands secrete bicarbonate, a buffer, and mucus. These two secretions are protective of the stomach lining. The majority of ulcers occur in the upper or non-glandular portion of the stomach. This is probably due to the lack of protection (bicarbonate and mucus) in this area against the hydrochloric acid being secreted in the lower (glandular) portion of the stomach. Whenever the upper portion of the stomach comes in contact with hydrochloric acid, damage to the lining and consequent ulceration may occur. The type of food a horse consumes and the period of time over which it is eaten seems to play a significant role in whether ulcers will develop. Horses which graze on free range pasture appear to have the lowest incidences of gastric ulcers, probably because the stomach is pretty much always full. Stabled horses on the other hand, fed on a schedule, will go through periods of the day when the stomach is relatively empty. During these times the upper non-glandular portion of the stomach may be in contact with the damaging hydrochloric acid. Other factors may also play a role in the development of stomach ulcers. Stresses of intense training, changes in routine and management may also be contributory. Regardless of the root cause the underlying pathology appears to be exposure of the unprotected non-glandular lining of the upper portion of the stomach to the secreted hydrochloric acid of the lower portion. The bacterium, Heliobacter pylori, incriminated as the cause of most human ulcers, does not appear to be of any significance in the horse. Foals, unlike adult horses may get ulcers in both the glandular and non-glandular portions of the stomach.
The signs of gastric ulceration in both foals and adult horses may vary greatly from no signs at all, to severe, life threatening colic. In foals, clinical signs are usually seen only when the ulcerations are advanced and may include grinding of the teeth, rolling up onto the back and salivating excessively. Yearlings, on the other hand, will often show recurrent colic, poor body condition, poor appetite and intermittent diarrhea. In adult horses the signs of gastric ulceration may be inapparent, subtle, obvious or severe depending on the individual and degree of ulceration. Subtle signs may include changes in attitude and performance. Affected horses may be “dull” or “grumpy” or aggressive and their performance may decline. More severely affected animals may show signs of recurrent colic, loss of condition, poor appetite, etc.
The excessive or prolonged use of the non-steroidal anti-inflammatory drugs, such as Phenylbutazone (Bute) and Banamine may result in ulceration of both the glandular and non-glandular portions of the stomach. This is probably due to the anti-prostaglandin effects of these drugs, as prostaglandin, a hormone, is a protectant against the detrimental effects of the hydrochloric acid and pepsin.
The definitive diagnosis of gastric ulceration must be made via endoscopy or “scoping” the horse’s stomach. In this procedure a long (2.8 meter), flexible fiberoptic endoscope is passed up the horse’s nose, through the nasopharynx, down the esophagus and into the stomach. The clinician is then able to visualize all areas of the stomach and evaluate the presence and severity of any gastric ulceration. If endoscopy is not practical then a presumptive diagnosis of gastric ulceration may be made on the basis of clinical signs, history, and complete physical examination. Fortunately because this is such a well recognized syndrome insurance companies are willing to cover the cost of treatment when appropriate diagnostics are performed. See article on Video Endoscopy.
Treatment of gastric ulcers generally involves the use of drugs that either reduce hydrochloric acid secretion or protect the stomach lining. In general, the use of acid suppressants is much more common. The two most widely used such drugs are Cimetidine (Tagamet) and Ranitidine (Zantac) and the three times daily oral treatments are continued for 3-4 weeks. Management changes to reduce stress and to decrease periods of an empty stomach should also be instituted. A newer drug, Omeprazole (Gastro-guard) has been approved for use in horses and it appears to be extremely effective in treating ulcers. This paste is administered once daily for 28 days. While these drugs all appear to be very effective in treating gastric ulcers, with clinical signs of improvement often seen within only 24-48 hours, they are quite expensive.
In summary, while gastric ulceration in horses now appears to be very common, most mild cases may be self healing without showing significant clinical signs or requiring treatment. However, more severe ulcerations may cause a variety of signs and interfere with the horses health and performance. We are fortunate to have drugs that are very effective in treatment of gastric ulceration as well as diagnostics to identify.