The Texas Animal Health Commission (TAHC) reports that laboratory tests have confirmed that a stallion in Texas is infected with contagious equine metritis (CEM), a highly contagious venereal disease of horses.

The Texas-born quarter horse had spent the 2008 breeding season in Kentucky, where CEM was detected in a stallion during routine testing in mid-December As of January 15, a total of nine infected stallions have been detected: four in Kentucky, three in Indiana, and one each in Wisconsin and Texas. All of the infected stallions have epidemiological links to one or more CEM-infected equine during the 2007 or 2008 breeding season. State and federal authorities are continuing to seek the source of the infection.

At least 38 states are involved in a nationwide epidemiological investigation and testing of about 275 horses that may have been exposed to CEM through natural breeding or artificial insemination. The disease can be spread among stallions, if strict biosecurity measures are not maintained during the collection of semen.

CEM is not routinely spread through casual contact or shared boarding facilities, and horses can be treated with disinfectants and antibiotics to wipe out the infection. Potentially exposed and infected equine animals are being held under movement restrictions by state animal health authorities, until they test negative for the disease or they complete veterinary treatment and are certified as CEM-negative.

Currently, the TAHC is working with accredited private veterinary practitioners to test another stallion and 21 mares with potential exposure to CEM. In some cases, CEM may cause infected mares to abort.

CEM is not known to affect humans. The equine disease was first detected in the U.S. in 1978, then again in 1979. In both instances, the limited outbreaks were eradicated.

Additional national CEM information may be found on the USDA’s web site at: http://www.aphis.usda.gov/newsroom/hot_issues/cem/index.shtml.