FAQ: What is CEM?

Contagious Equine Metritis (CEM) is a venereal disease of horses caused by a bacteria, Taylorella equigenitalis, that is spread through breeding. When infected, CEM results in a mare developing an acute uterine infection which may prevent her from conceiving, or cause an early pregnancy loss. Stallions can also carry the bacteria, but do not show outright clinical signs of the disease. USDA regulation requires that all imported horses of breeding age (mares and in tact stallions, over 2 years or 731 days of age) from any country known to have CEM, must go to an approved USDA CEM Quarantine Facility for testing and treatment.