Editor’s Note: This is an excerpt from Chapter 2 in Care and Management of Horses, written by respected equine author Heather Smith-Thomas. 

Domestication has created problems for the horse, including stomach ulcers. Stress of confinement and unnatural conditions, stress from emotional and physical aspects of athletic careers–all the stresses that go with trying to adapt to human management–can create ulcers in horses. Ulcers, once thought to be mainly a problem in confined foals, also plague adult horses. Racehorses and other performance horses have an especially high incidence.

Research reported at the 1998 American Association of Equine Practitioners (AAEP) convention in Maryland showed that gastric ulcers affect up to 90 percent of performance horses and that many of the factors associated with intensive training and conditioning contribute to ulcer formation.

Stomach ulcers occur when the lining is damaged by excessive acid or by impairment of the stomach lining’s natural protection. Signs of ulcers are dullness, decreased performance, poor appetite, poor condition, rough hair coat, and poor weight gain. Often the problem is not obvious; the horse just isn’t doing as well as he should be. Some horses adjust to the stress better than others, but it’s hard to predict which ones will have problems