Equine Gastric Ulcer Syndrome

A New Look into the Equine Stomach

Up until roughly the last decade, the equine stomach was somewhat of a mystery to practitioners. Today, with the increasing use of new powerful video endoscopy equipment, a great deal of knowledge has been gained about the equine stomach. A new clinical disorder called Equine Gastric Ulcer Syndrome (EGUS) has been brought to attention and recognized as an important and common cause of colic, ill-thrift, weight loss, and poor performance in the equine species.

The equine stomach is quite unique from other species in that it contains two distinct regions. The upper 1/3 of the stomach functions to store feed and ingesta while the lower 2/3 of the stomach is the glandular portion that secretes acids and enzymes to digest feed. The structure of the non-glandular stomach makes it susceptible to ulcerations since it is not designed to deal with acidic gastric contents.

There are many factors involved in the development of EGUS. Stress, exercise, diet, illness, excessive NSAID use (Bute, Banamine), and transport are just a few factors that can lead to alterations in the structure of the stomach wall that allow gastric acids and enzymes to damage the stomach lining.

Gastric ulcers are most commonly found in horses that are being used intensively but clinical problems with ulcers have been found in all types of horses. Diet and exercise are two of the biggest factors leading to the development of gastric ulcers. Contraction of abdominal muscles during exercise decreases the size of the stomach and pushes acidic contents into upper, unprotected portion of the stomach.\tab Diet is another very large factor in the development of ulcers. The ingestion of carbohydrate-rich diets (concentrates, sweet feed, etc.) leads to the production of acidic by-products that can cause damage to the stomach lining and lead to the formation of gastric ulcers. In general, horses are designed as grazing animals and will graze approximately 18-hours a day, so their digestive system is set-up to continually secrete digestive acids and enzymes, even into an empty stomach. Horses that are fed "meals" are still continually secreting acids into their stomach even though there is no feed present to soak up the acids and prevent them from coming into continual contact with the wall of the stomach. Pasture grazing or free-choice feeding prevents the accumulation of acid in an empty stomach.

Horses with gastric ulcers can show a variety of clinical signs. Sometimes they can be very vague and non-specific. They include:

1. Colic, especially low-grade and recurring
2. Poor appetite, picky-eaters, or reluctance to finish grain
3. Poor hair coat
4. Weight loss
5. Poor performance, behavioral problems, decreased endurance

Unfortunately, there is no consistent relationship between the severity of gastric ulcers and clinical signs. The most reliable method of diagnosis is through imaging the stomach after the horse has been fasted for 24-hours with a video endoscope (a fiberoptic scope with a video camera that allows you to see the entire lining of the stomach) and correlating the findings with clinical signs.

The main premise behind treating gastric ulcers is decreasing stomach acidity with acid-inhibiting drugs. These include histamine-blocking drugs that decrease the stimulus for acid secretion, anti-acids, and acid pump inhibitors (omperazole). Omperazole has been found to be the most effective in the treatment of ulcers and horses can be ridden and trained during treatment and still heal.

Preventing gastric ulcers can be very challenging but is the key. Some horses seem more susceptible to developing ulcers than others. Feeding management needs to be modified to promote more continuous roughage consumption and less grain feeding. Alfalfa hay has actually been shown by research to be very beneficial in preventing gastric ulcers because it is high in calcium and proteins that are natural buffers to acidity in the stomach. Continuous consumption of feed through pasture turn-out is ideal and much better than meal feeding . Since pasture turn-out is not always available or realistic for some horses, feeding predominantly alfalfa hay morning and night with free-choice grass hay throughout the day is one management route to take. Corn oil is another supplement that can be added to the feed because it helps stimulate the production of hormones that naturally increase blood flow to the stomach. A 1000-lb. horse can be fed as much as ½-1 cup twice daily (most horses will find ¼ to 1/2 cup palatable and need to be introduced to it slowly). Watch those easy keepers though as it will help to put weight on them! Finally, for horses that have had ulcers in the past or are under high amounts of strenuous training or stress, a preventative dose of omperazole can be given to keep the development of ulcers at bay.

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