Contagious Equine Metritis

Contagious Equine Metritis (CEM) is a sexually transmitted disease among horses caused by the bacteria Taylorella equigenitalis.  Clinical signs may include a mucopurulent vaginal discharge in up to 40% of affected mares, abortion, and infertility.  Stallions typically show no clinical signs. Stallions and mares can become chronic carriers of CEM and be sources of infection for future outbreaks.  The transmission rate is high and naturally occurs by mating, but contaminated instruments and equipment may and indirect source of infecting mares and stallions.  The bacteria can also be spread via semen collected for artificial insemination.


The Merck Veterinary Manual: Contagious Equine Metritis

USDA Contagious Equine Metritis Information

USDA Equine Import and Export Information

Equine Disease Communication Center: Disease Outbreak Alerts