April Knudson, DVM, is an equine specialist with Merial Veterinary Services. She has a special interest in equine gastrointestinal health, infectious disease, and lameness. She holds a doctor of veterinary medicine from the University of California, Davis. Here, she answers a question about the use of bismuth subsalicylate in horses.

Q. I’ve heard of people giving bismuth subsalicylate, commonly known as the human product Pepto-Bismol, to their horses to help treat or prevent stomach ulcers. Does it work?

A. Bismuth subsalicylate is used in people to treat diarrhea and gastric distress such as nausea, indigestion and heartburn; however it is not labeled for use in any animal. In the case of horses with ulcers, the use of bismuth is not recommended.

Once in the gastrointestinal tract, bismuth subsalicylate can be converted to sodium subsalicylate, which can cause gastric irritation. Additionally, salicylates, like aspirin, decrease prostaglandin secretion, which can further damage an already compromised stomach lining. For these reasons, bismuth is contraindicated in horses