The equine stomach, unlike most mammals, has 2 distinct divisions: the squamous region and the glandular region. The line of demarcation between the regions is known as the margo plicatus. Gastric ulcers can be found in any area of the stomach, but are most commonly found in the squamous mucosa and are generally most severe along the margo plicatus. When ulcers are present in the glandular region of the stomach, they most frequently are located around the pylorus, which is the terminal opening of the stomach that leads to the small intestine.
Gastric ulcers can occur in adults or foals, may vary in severity, and have a multiple causes. Unlike humans, a horse’s stomach continuously secretes hydrochloric acid to aid in digestion; therefore, the acidity in a horse’s stomach increases between periods of eating. Consequently, circumstances that prolong the amount of time a horse does not eat, such as illness or intense exercise, will increase the amount of time the lining of the stomach is exposed to higher concentrations of hydrochloric acid. The increased exposure to hydrochloric acid will, in turn, increase the risk of the horse developing gastric ulcers. In addition, the use of several anti-inflammatory medications such as phenylbutazone (‘bute’) or Banamine® is associated with an increased risk of gastric ulcer development.
Clinical signs observed in horses with gastric ulcers are variable. Some of the more common signs include: mild to moderate abdominal pain, a failure to consume grain completely, the loss of body weight, a poor hair coat and lethargy. Foals with gastric ulcers will frequently grind their teeth, salivate, lose weight and demonstrate signs of colic. The only way to confirm the presence of gastric ulcers is by passing a long endoscope into the horse’s stomach (gastroscopy) facilitating direct visual inspection of the lining of the stomach. Generally, gastric ulcers are graded on a scale of 0 to 4 based on their severity. A grade 1 ulcer is considered mild as it is superficial and small while grade 3 ulcers are considered more severe as they are deeper and bleeding.
Treatment and Prevention
The mainstay of treatment for gastric ulceration in horses is to suppress the production of hydrochloric acid in the stomach. Two drugs that are most frequently used in equine medicine for this purpose are omeprazole (GastroGard®) and ranitidine (Zantac®). Horses are generally treated with these drugs for 1- 2 months, but the duration of therapy should be dictated by the findings of a repeat gastroscopy.
Another drug commonly used to treat gastric ulceration is Sucralfate (Carafate®), an oral medication that protects the lining of the stomach from further insult. Once gastric ulcers are eliminated, studies have demonstrated that omeprazole, administered at a lower dosage, will prevent the recurrence of gastric ulceration. Certain diet changes are also helpful in lowering the risk for gastric ulceration, such as decreasing the amount of grain or concentrate the horse eats, offering free choice grass hay, and feeding alfalfa hay.
If you suspect your horse has gastric ulcers, please consult your veterinarian. He or she will help you formulate diagnostic and treatment plans specifically for your horse.
Lauren Danskin, DVM