Most of you have heard of MRSA infections in humans and these infections are also becoming a problem in equine medicine. MRSA is the acronym for methicillin resistant staph aureus, a bacterium that is resistant to many common antibiotics such as penicillin and cephalexin as well as many other antibiotics. Consequently, this infection is difficult to treat. Dr. Scott Weese indicates in the Equine Compendium that the incidence of MRSA infections is unclear but it seems to be on the rise.

MRSA is carried by about 5% of horses in their nasal cavities, and a high percentage of folks who work with horses have the organism growing in and on their bodies and these infections can be transmitted to people. The diagnosis of these infections is by culturing areas of infection and in horses treatment of these infections in is usually with an antibiotic called chloramphenicol. Also, skin and wound infections can be treated topically with various disinfectants that are also useful. It would be nice to treat horses to kill the organism and prevent them from carrying the resistant bacteria. However, there is no evidence that treatment with antibiotics will eliminate the organism and many horses will eliminate the infection naturally. For this reason and the fact that we are trying to prevent further antibacterial resistance, antibiotics are not recommended. This is becoming such a concern that the Ontario Veterinary College screens all horses for MRSA when they enter their hospital and all infected horses are isolated. Gloves are used when dealing with equine discharges and wounds and this is probably a good idea for all of us dealing with horses to help prevent MRSA infection.