Contagious Equine Metritis

Contagious equine metritis (CEM) is a highly contagious venereal disease of horses caused by the bacterium Taylorella equigenitalis. It can be passed through breeding or via contaminated equipment. The bacterium that causes CEM can also be transmitted indirectly via semen during artificial insemination. CEM is important not because it is a deadly disease (it isn’t), but due to the massive economic losses that can be associated with the disease as result of its devastating effects on reproductive efficiency.

Stallions do not develop signs of infection, but CEM should be suspected in mares that have an early return to estrus after breeding to a fertile stallion and/or the presence of vaginal discharge. After diagnosis and treatment, the prognosis for recovery is excellent.