California Among 39 States Testing Horses for CEM

California is among 39 states testing horses that might have been exposed to a highly contagious venereal disease of horses, contagious equine metritis (CEM). 

California Department of Food and Agriculture veterinarians have quarantined 14 mares and are working with the USDA and regulatory veterinarians in other states to identify any additional exposed horses as this nationwide disease investigation unfolds. Following a course of negative cultures and treatment, the mares will be released from quarantine.

In mid-December 2008, a CEM-infected Quarter Horse stallion was detected in Kentucky during routine testing for international semen shipment. The USDA and Kentucky animal health authorities quickly initiated a disease investigation, leading to the identification of more exposed horses. To date, nine stallions have been confirmed to be infected: four in Kentucky, three in Indiana, one in Wisconsin, and one in Texas; and a total of 334 exposed stallions and mares in 39 states have been identified and placed under quarantine by state animal health authorities, pending test results.

CEM is considered a bacterial foreign animal disease and has only been detected in the United States on three previous occasions, in 1978 in Kentucky, 1979 in Missouri, and in 2006 in Wisconsin. In all instances, the disease was controlled and eliminated quickly. CEM is not known to affect humans or other livestock. It is spread between mares and stallions during mating or with infected semen used in artificial insemination. It can also be transmitted on contaminated breeding equipment. Stallions do not exhibit any clinical signs, but the infection may cause fertility problems in mares.

Additional national CEM information may be found on the USDA's Web site.

Stay on top of the most recent Horse Health news with FREE weekly newsletters from Learn More

Free Newsletters

Sign up for the latest in:

From our partners