Pigeon Fever, otherwise know as Dryland Distemper, is considered to be one of the most frequent infectious diseases in California. The symptoms and signs include external abcesses, seen as swelling at the horse’s chest (most common) , internal abscesses which occur on the kidneys, liver or spleen, infection of the limbs, ("ulcerative lymphangitis"), decreased appetite, fever, lethargy, weight loss and signs of respiratory disease or abdominal pain. The bacteria that causes pigeon fever is Corynebacterium pseudotuberculosis, and produces various exotoxins which cause pain, infection and increase the spread of the bacteria. According to a study done by Dr. Sharron Spier at the UC Davis School of Veterinary Medicine, external abscesses occurred in 91% of the cases, internal abscesses occurred in 8% of the cases, and ulcerative lymphangitis occur in 1% of cases.

According to UC Davis, "Until a protecting bacterin or toxoid us developed for horses, we can only suggest that horse owners in endemic areas practice good sanitation and fly control and avoid unnecessary environmental contamination from diseased horses."  The use of feed through insect regulators containing cyromazine (a chitin inhibitor) is safer than products that contain organophosphates and will control vector populations.  Maintaining proper sanitation, disposal of contaminated bedding and disinfection will reduce disease incidence as well as proper wound care.