Contagious equine metritis.

Contagious equine metritis (CEM) is a highly contagious venereal infection of equids caused by Taylorella equigenitalis, a bacterium with fastidious growth requirements. A disease of major international concern, CEM can be the cause of short-term infertility and, very rarely, abortion in mares. Unlike the mare, stallions exposed to T. equigenitalis do not develop clinical signs of disease. CEM is transmitted by direct or indirect venereal contact. The carrier state occurs in the mare and the stallion and carrier animals are frequently the source of infection for new outbreaks of the disease. There are streptomycin-sensitive and -resistant biotypes of T. equigenitalis, and diagnosis is based primarily on culture of the bacterium from its predilection sites in the reproductive tract of the mare and the stallion. Treatment modalities are available for elimination of the carrier state. Prevention and control of CEM is achievable through a comprehensive programme of breeding farm management that includes early detection and treatment of carrier mares and stallions.