EGUS is a common problem in horses and foals. Acids are the important causative factors and current therapy targets the suppression of gastric HCl and creation of a permissive environment for ulcer healing. Diagnosis is based on history, clinical signs, gastroscopy, and response to treatment. Of the products available, only GastroGard (FDA approved) and ranitidine have been shown to be efficacious in the treatment of EGUS. Ranitidine is often associated with treatment failure as a result of incorrect dosing and lack of owner compliance, because of the three times daily dosing required. Also, EGUS occurs in critically ill neonatal foals, but the pathogenesis may be different than in adult horses and acid-suppressive therapy may not be as effective.