CEM Exposure: North Dakota Mare Quarantined

A North Dakota mare has been quarantined after state animal health officials learned it had been exposed to contagious equine metritis (CEM), a highly contagious venereal disease of horses.

"The animal and all other horses on the premises have been quarantined--no other horses are allowed on or off the property," said Susan Keller, DVM, the state veterinarian. "These restrictions remain in effect until the animal has been tested three times with negative results."

Keller said the mare was artificially bred with infected semen from one of four Kentucky stallions that have been diagnosed with CEM. The disease causes infertility in mares and may cause spontaneous abortions. It can be treated with antibiotics and disinfectants.

"The good news is that the mare is pregnant and showing no signs of aborting," Keller said. "The other good news is that the disease is spread only through sexual contact or artificial insemination, so the mare does not pose a risk to other horses at this time."

The causative organism of CEM, Taylorella equigenitalis, was detected Dec. 10, by veterinary pathologists at the University of Kentucky in a culture from a Quarter Horse stallion. Since then three other stallions from the same premises have tested positive for the disease.

Federal officials are tracing horses to owners in 24 states. It is estimated that approximately 750 to 800 mares were bred to the 22 stallions on the Kentucky farm, including about 160 mares inseminated by the four infected stallions.

No mares have tested positive for CEM to date.

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