Horses can be infected with Brucella abortus or B suis. Suppurative bursitis, most commonly recognized as fistulous withers or poll evil (see Fistulous Withers and Poll Evil), is the most common condition associated with brucellosis in horses. Occasionally, abortion has been reported. It is unlikely that infected horses are a source of the disease for other horses, other animal species, or people. Brucellosis in horses is very rare in the USA because of elimination of the disease in cattle.