Stomach infections with the bacterium Helicobacter pylori have been associated with gastric ulcers in humans. Antibiotic therapy can be indicated in some cases of human gastric ulcers for this reason. However, H. pylori infection has not been associated with gastric ulcers in horses. Any oral antibiotic has the potential to cause diarrhea or other gastrointestinal upsets in horses.

In general, antibiotics should be administered to horses only for known infections. Ideally, a culture of the infected site is performed to confirm bacterial infection and determine which antibiotics are most likely to be effective.