The recent (or, I guess, not so recent, since it seems to have been lingering in the background for a while) contagious equine metritis (CEM) outbreak in the US was a good demonstration of the potential impact venereally transmitted diseases can have on the horse industry. Concerns about such things are greatest in breeds that only allow live cover, since an individual stallion may be exposed to a large number of mares every year, and with the mobile nature of the horse population, it’s possible for one infected horse to disseminate an infection widely across or between countries.

While CEM is probably the highest profile venereal disease in horses, it’s not the only one. Other pathogens like equine arteritis virus and equine herpesvirus type-3 (equine coital exanthema virus) are also of concern, along with various opportunistic bacteria.

Proper management and infection control practices can greatly reduce, but not eliminate, the risk of sexually transmitted infections in horses. Unfortunately, such practices aren’t always used. Sometimes it’s because of lack of consideration or laziness. Sometimes it’s because of lack of awareness. To help improve awareness and make it easier for people to take appropriate precautions, the American Association of Equine Practitioners (AAEP) has recently released Biosecurity Guidelines for Control of Venereally Transmitted Diseases. It’s an excellent resource for veterinarians and horse owners, and should be part of the infection control program for anyone breeding horses.