The development of gastric ulcers in horses, known as Equine Gastric Ulcer Syndrome (EGUS), can be a common cause of decreased performance, weight loss, behavioral changes, and colic.

Potomac horse fever (PHF) is caused by the intracellular bacteria Neoricketsia ristcii. Horses are typically affected during the late spring, summer, and fall months. Many cases are near bodies of water and are commonly seen in the midwest and northeast regions of the United States.