California Mare Tests Positive for Contagious Equine Metritis

A 17-year-old Lusitano mare from California has been confirmed positive by the National Veterinary Services Laboratory for Taylorella equigenitalis, the bacterium that causes contagious equine metritis (CEM).

"Our goal is to isolate this disease and limit its spread as much as possible by quarantining and treating the infected mare and any other affected animals," said California State Veterinarian Annette Jones, DVM. "We have had success in the past in tracking and eradicating this disease and we are confident in the measures we are taking to protect our horse population. Peak breeding season is getting under way, so we encourage horse owners to work with their veterinarians if they have any questions or concerns."

The positive mare was presented to a private practitioner for infertility concerns and samples were submitted for culture. The mare remains under quarantine while being treated for the disease with antibiotics. The epidemiologic investigation of the positive mare is currently in progress. Information collected to date indicates that her breeding activities were limited, and no horses located outside of California are currently known to have been exposed.

CEM is a contagious bacterial infection spread between mares and stallions during live breeding or artificial insemination with infected semen. It can also be transmitted on contaminated breeding equipment. CEM is not known to infect other livestock or humans. Stallions infected with CEM do not exhibit any clinical symptoms, but infection in the mare can cause fertility problems.

CEM is considered a foreign animal disease in the United States. The disease was previously detected in California in 2009 and 2010 and quickly eradicated. There is no known relationship between the positive mare and any horses associated with previous U.S. cases of CEM. Further, testing at the NVSL confirms that this isolate does not match those of any other isolates from previous CEM detections in the United States and do not match any isolates ever found on post-entry CEM quarantine testing of horses entering the United States from CEM-affected countries.

VIDEO: Contagious Equine Metritis: Testing and Treating Mares

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