As previously mentioned, horses are designed to be grazers with frequent ingestion of roughage. Because the horse’s stomach constantly secretes acid from the glandular region, gastric ulcers can develop when the animal is not fed often enough to allow for the proper neutralization of the acid by feed. While in humans, bacteria tend to be the cause of gastric ulcers, in horses, ulceration is caused by the erosion of the stomach lining due to prolonged exposure to the acid which is normally present. There are a number of man-made causes of gastric ulcers besides too infrequent feeding schedules. Environmental and physical stresses can lead to their development. Training, showing, shipping, and introducing new horses into an established herd are all potential causes of ulcers. In cases of strenuous exercise, the blood flow to and emptying capacity of the stomach can be reduced which can increase the likelihood of ulcer formation. Stall confinement and hospitalization for other ailments may result in the development of ulcers in horses of any age, with foals being especially susceptible. Finally, long-term treatment with any non-steroidal anti-inflammatory drug such as Flunixin Meglumine, Phenylbutazone, or Ketoprofen can lead to a decrease in the production of the stomach’s protective mucus layer, resulting in an increased risk of the development of ulcers in the glandular portion of the stomach.
As with dental issues, horses with gastric ulcers frequently do not show obvious clinical signs in the early stages of disease. Subtle signs such as a decrease in appetite, weight loss, poor hair coat, and diminished performance can frequently initially be missed. Other signs of ulceration such as colic and bruxism (grinding of the teeth) are much more obvious.
The standard method to definitively diagnose the presence of gastric ulcers is via gastroscopy—the examination of the surface of the stomach through an endoscope. Feed is withheld for 12 to 24 hours and water for 2 to 3 hours prior to the procedure to ensure that the stomach is sufficiently empty. The horse is lightly sedated and occasionally twitched and the endoscope is fed through a nostril and down the esophagus into the stomach where the lining can be evaluated. While the esophagus and stomach can be readily visualized via endoscopic examination, the presence of ulcers in the hindgut or colon can not be identified via an endoscope. Ulceration of the equine colon is a topic which will be reviewed in a future ImmuBiome article.
The primary goal of any therapeutic regimen for the management of gastric ulcers is to reduce the production of acid by alleviating the physiological, environmental, training and husbandry stresses on the horse. Ideally, horses should have free access to hay or grass. If this is not a viable option, then they should be offered smaller and more frequent meals of high-quality hay and grain free from toxins or artificial ingredients. More frequent feedings result in an increase in the production of saliva which acts as a natural antacid. Opportunities to socialize with other horses, have some form of turn-out, and the implementation of an appropriate training program are all practical ways of reducing the likelihood of ulcer formation. In cases of active gastric ulcer formation, a product which is specifically labeled to prevent and/or treat ulcers is indicated. Clearly, prevention through proper husbandry, low sugar, and training practices is the key to reducing the likelihood of gastric ulcer formation.
CONCLUSION Hopefully this article has been informative on the subject of normal versus diseased states of the upper digestive tract. Future articles will focus on the anatomy and health of the intestinal tract as well as its commonly seen diseased states. Diet, supplements and the normal microbiome, (how it functions, and how it changes with poor diet and husbandry) will be covered in addition to the idea of probiotics. Metabolic issues and how they can be correlated with improper diet will be discussed as a final installment of the gastrointestinal series.