Gastroscopy is the evaluation of a horse's stomach and is an important component in diagnosing causes of colic, weight loss, inappetance, and poor performance. Gastric ulcers are most commonly located along the margo plicatus and the cardia. The margo plicatus is the separation between the top and bottom portions of the stomach, and the cardia is the area of the stomach where food enters.

A 3-meter endoscope is required to perform gastroscopy in horses (1-meter endoscopes are not long enough to reach a horse's stomach). Prior to gastroscopy, the horse must be fasted for a minimum of 18 hours (no hay, grass, or grain) and should not receive any water for 4 hours prior to the examination. The horse is temporarily sedated for the examination, and the results of the gastroscopy are documented on a digital printer.

If gastric ulcers are diagnosed, the horse is administered Gastrogard®. Fortunately, gastric ulcers respond very successfully to this medication over a 28 day period.