Contagious Equine Metritis (CEM) is a non-systemic, venereal disease of equines that causes short-term infertility in mares and rare abortion. The etiological agent is Taylorella equigenitalis, a fastidious, microaerophilic, Gram-negative coccobacillus. CEM was first recognized in the US when it was found in Thoroughbred stallions and mares in Kentucky in 1978.