Recently we have received questions on gastric (stomach) ulcers. This is a topic that has been and is continuing to be studied extensively. Ulcers occur in a high percentage of horses — anywhere from 38 percent to 88 percent, depending which article you read and depending on the occupation, breed, management, and so forth. In this column, we’ll focus on the symptoms, treatment, and prevention.
First, let’s describe a gastric ulcer. It is a non-healing wound of the lining of the stomach. They can be in the top part of the stomach, which does not secrete stomach acid, or it can be in the lower part of the stomach which does secrete stomach acid. The most common location is at the junction of the two areas, called the margo plicatus. No matter the location, stomach ulcers can be a nagging problem to the horse that can actually get bad enough to perforate and lead to the horse’s death.
The symptoms of ulcers have been attributed to many manifestations. Some horses have no symptoms at all. Some will have colic symptoms — colin being defined as abdominal pain. It is a very vague term that some horse owners attribute to a small set of problems, but the pain from ulcers would be included. Some horses will be uncomfortable with cinching, and other clinical signs are grinding of teeth, weight loss, poor performance, and poor appetite. The variability of clinical signs can sometimes make the diagnosis challenging without any additional testing. The only definitive way to diagnose ulcers is by gastroscopy. This involves passing a 3-meter endoscope into the nostril and down into the stomach so that we can actually see what is going on in there!
The treatment for ulcers is done by a combination of modalities. First is management. Increasing the roughage of the diet (hay) and decreasing the concentrates (grain). Roughage takes longer to eat and also increases the amount of saliva produced. Saliva is the natural antacid, so more is better. Grains tend to make more volatile fatty acids (VFAs). These “VFAs” tend to produce more ulcers.
To take this a step further, you can go to a slow feeder. Horses are designed to be eating most of the time. This constant, slow eating will be mimicking the natural design of how horses should eat, thus being the best. The next step in treatment is usually trying to reduce stomach acid. Drugs used for this are usually omeprazole (Gastogard®, Ulcergard®, etc) or ranitidine (Zantac®). They both work by different ways of reducing the acid. Omeprazole is usually given once a day. It is what is called a proton pump inhibitor. By inhibiting this pump, the glands in the stomach cannot produce as much acid. Ranitidine is usually given 2-3 times a day. It works by binding to a receptor called the histamine 2 or H2 receptor. This blocks a pathway that leads to stomach acid production. The next type of treatment would be with a gastroprotectant. Sucralfate is the one most commonly used. The drug is activated by stomach acid and binds to the exposed tissue of an ulcer. The idea is that is forms a barrier between the ulcer and the stomach acid to allow for faster healing. A less commonly used drug is misoprostol. It actually works two ways. First it decreases acid production; second, it increase mucus production. It is not used as much due to cost. All of these treatments are done for varying times, based upon the the location of the ulcers and the response to treatment.
Prevention starts with some changes we have already discussed: changing the diet and the frequency of feeding. Certain drugs predispose horses to ulcers. The most common group is non-steroidal anti-inflammatory drugs. These include phenylbutazone (bute) and flunixin meglumine (Banamine®). These commonly used drugs decrease the amount of the protective mucus that is produced in the stomach. The underlying tissue is then exposed to more acid and can be damaged. These drugs have their place, but overuse can have some severe side effects including ulcers. Often times when these drugs need to be used, we can administer ranitidine or omeprazole to minimize the damage to the lining of the stomach. Lastly, limit stress. Horses are a herd animal. They need to be able to socialize with others. Make sure your horses can at least see each other so they can some type of interaction. If you are going to be traveling or showing, consider using omeprazole prophylactically starting just before your showing or traveling and continue it until you return home. Ulcergard® is labeled for this and can be purchased without a prescription.
We have briefly touched on the symptoms, treatment, and prevention of gastric ulcers. This type of ulcer is very common in our hard working horses. If you notice any of these signs, be sure to discuss it with your veterinarian and come up with a plan to diagnose and treat them. After that, make a plan to enact changes in your husbandry and feeding programs to minimize the chances for the ulcers to return.