University of Kentucky Assists in CEM Investigation

A 16-year-old Quarter Horse stallion residing in Kentucky tested positive for the causal agent of contagious equine metritis (CEM), a bacterium Taylorella equigenitalis, on Dec. 10 (read more). CEM is considered a foreign animal disease that occurs in breeding populations in various countries in the world. The test was performed by the University of Kentucky Livestock Disease Diagnostic Center (LDDC) and reported to the Kentucky state veterinarian.

According to officials, two additional stallions on the same farm have now also been confirmed positive. The original stallion has completed treatment, and the additional cases are being prepared for treatment. All horses identified as at risk of exposure are under quarantine and undergoing testing. Researchers at UK's Maxwell H. Gluck Equine Research Center and LDDC have been informed and are working closely with state veterinarian Robert Stout, DVM, and the USDA.


Watch a video interview on contagious equine metritis with Dr. Peter Timoney.
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According to Gluck researchers, CEM is a sexually transmitted disease that only affects members of the equine family. It does not present an immediate risk of spread to the general horse population as long as state and federal regulations are followed. The disease can only be transmitted by sexual contact and is most frequently spread when a stallion breeds a mare. It may also be transmitted through artificial insemination or contact with contaminated hands or any objects that have been in contact with the genitalia of infected stallions or mares. Stallions are symptom-free carriers of the bacterium Taylorella equigenitalis. Infected mares can develop inflammation of the reproductive tract, which can result in temporary infertility.

Researchers said there are no reports of transmission of infection to pregnant mares except at the time of breeding. Only two confirmed cases of abortion due to this bacterium have been reported in the past 30 years. CEM can be treated effectively with a wide range of disinfectants and antibiotics. Strict hygiene should be observed after contact with horses that test positive for Taylorella equigenitalis. CEM is not known to be transmissible to humans.

Mares imported into Kentucky from CEM affected countries, or mares found to be infected, are required by federal and state regulations to undergo testing and treatment and remain in quarantine until confirmed negative for Taylorella equigenitalis. All stallions imported into Kentucky from a CEM affected country, or stallions found to be infected, are required to be quarantined and to undergo similar testing and treatment until they are determined negative for the causal agent of CEM.

In contrast to other infectious diseases, such as equine herpesvirus neurologic disease, equine influenza, or equine viral arteritis, CEM is not spread by close physical contact or via airborne transmission, said Gluck researchers. The horses that have been confirmed carriers were moved to Kentucky from various states prior to the start of the 2008 breeding season. While located in Kentucky, there has been no history of any of these stallions having live covers.

State and federal control measures have been implemented on the affected farm, and there is currently no risk of spread to other horses in Kentucky. An investigation remains ongoing, and while additional horses from the farm may test positive, there is no evidence suggesting that the organism has spread beyond the group of mares and stallions first identified as at risk of exposure.

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