Gastrointestinal Ulcers

How Can We Deal With Them?

By Kerry J Ridgway, DVM, CA

the last issue of

The Aiken Horse,

we discussed the incredible preponderance of horses that have ulcers in their digestive tracts. In that article we also discussed the largely unrecognized performancelimiting muscular-skeletal problems and ?behavioral? problems that go hand in hand with ulcers in horses. Since we have recognized that ulcers are a significant problem in horses for only about ten years, our knowledge is still limited. We are still learning and seeing the problem in more depth. What I, as a rider and clinician, am now recognizing is that through the years we have unknowingly condemned hundreds of thousands of horses to the trash heap. We simply did not know that so many ?hard keeping hoses,? ?bad disposition horses? or ?poor performing horses? were suffering from gastrointestinal tract (GI) ulcers. Looking back, some dispositional issues were so severe that afflicted horses could be extremely aggressive and dangerous to handle. Perhaps many of these animals could have been top horses if we had simply known how diagnose and deal with their ulcers. The sad truth is that many horses are still being condemned for these very same reasons. Because of a lack of knowledge about ulcers, they are being called failures as performance horses or deemed too difficult to work with. In my practice, I see horses every day that were formerly mellow become nervous, agitated or even downright mean. So let us talk about how to deal with GI ulcers. In the following discussion, I am going to refer to the horse as ?he? or ?him?, but the reader should understand that I am referring to both genders in all instances. The first thing that we must acknowledge is that equine ulcers are a manmade disease. We have taken a nomadic herbivore evolved to graze as much 20 hours a day (often on low quality forage), placed him in confinement and bulked him up with ?high quality? hay and massive quantities of grain that he would never have seen in his natural state. The ?high quality forage? that we feed is really designed to fatten cattle or increase their milk production. It is not the ?lower quality? forage that nature designed the horse to eat. Perhaps we should answer the question, ?Are we feeding the horse to eat or to produce more milk?? Adding insult to injury, we don?t even allow the horse to eat and cover some distance over the 18?20 hour grazing period for which nature designed him. Instead we add to his stress by confining him to a stall or a small area. Then we feed him twice, or if he is lucky and we are good managers, we feed three times a day. Often he is alone, or out of sight of his companions ? totally against his nature as a herd animal. But we are not through yet. We transport him to strange locations, often over long distances, often without the companionship of horses that he knows, change the water that he is used to, perhaps change the forage he has at home and again confine him in a very small box stall, or tie him to a trailer for long hours at a time. I am not so naïve as to suggest that we are going to suddenly change everything in our management and use of the horse. That is a fact of life and so are the consequent ulcers. However, it is possible to find ways to mitigate the environmental stresses and improve our feeding and management practices. So, our next need is to understand a bit of anatomy with regard to the horse?s digestive tract and a bit of the physiology of how horses digest food. This will help us come up with common sense answers to the question of how we should feed and manage our horses. It will also help us to understand what types of medicines and nutritional factors we can use to treat ulcers and prevent recurrences.

The Digestive Tract and Equine Digestion

Let?s start with the horse?s digestive tract. If it were to be stretched out to its full length, it would be a full city block long. The stomach portion is one of the smallest parts of the system: it can hold only two or three gallons of material at a given time. Considering the large amount of food a horse consumes in a day, the stomach must process the food pretty rapidly. The food then moves into the small intestine and from there into the large bowels. So, in relationship to stomach ulcers, the key point is that the stomach is geared to eating small amounts on a nearly continuous basis and not large amounts two or three times a day. The horse evolved as a grazing animal, right? Add to this the fact that the glandular portion of the stomach (located in the bottom portion of the organ) secretes well over a quart and a half of hydrochloric acid every hour on a 24/7 basis whether food is present or not. If no food is present for long periods, this acid can literally start digesting the lining of the stomach itself. This phenomenon is even more likely to occur when the horse is in exercise. During exercise, the tightening abdominal muscles compress the stomach and move acid up from its bottom portion. During a canter or a gallop, the horse?s viscera (that city-block-long coil of intestines and bowels) are propelled forward, essentially slamming into the stomach and compressing it against the diaphragm. The result is ?splashing? of the acids (hydrochloric, volatile fatty acids and bile acids) up and onto the upper part of the stomach. The lower part of the stomach, in addition to producing the acid, receives protection by also producing mucous. The upper or non-glandular part has no protection and thus is susceptible to damage by the acids. The upper portion has squamous epithelium ? not dissimilar in a way to our skin, and you are aware of the effect of acid on our skin. Add grain to the horse?s diet and we compound the acid load problem because grain digestion, as it starts in the stomach, is broken down into volatile fatty acids and adds to the hydrochloric acid and bile acids already present. Grains empty from the stomach more quickly than forage materials and progress into the small intestine. The larger the grain portion, the quicker the emptying. In the small intestine, digestion is aided by enzymes that break down the starch and

72 The Aiken Horse April/May 2009