Affected horses often need intravenous fluids to combat diarrhea, one of the most common clinical signs of both salmonellosis and colitis. | Photo: Anne M. Eberhardt/The Horse

Salmonellosis and colitis–two equine ailments that are commonly associated with each other–are a bit like the chicken and the egg: you don’t always know which came first, said Jamie DeFazio, CVT, VTS-EVN, nursing supervisor at the University of Pennsylvania School of Veterinary Medicine’s New Bolton Center, in Kennett Square.

“Colitis (inflammation of the large or small colon) can either develop as a result of salmonellosis, or can be the primary condition that predisposes the horse to salmonellosis,” she said during a presentation at the American Veterinary Medical Association Convention, held July 16-19 in St. Louis, Mo.

Although the two ailments commonly occur in tandem (especially in clinical settings, DeFazio noted), they are in fact two different problems that can arise independently as well