Farm Talk

May 5, 2009

Veterinarian shines light on equine disease

by Mary Lou Peter

For many horse owners, springtime means foaling and breeding time. It also means they should be aware of a venereal disease in horses that can cause infertility in mares, according to a Kansas State University equine veterinarian.

Although it has been found in several states since December, 2008, no cases of contagious equine metritis (CEM) have been confirmed in Kansas horses to date, said Maria Soledad Ferrer, an assistant professor in K-State´s Veterinary Medicine Teaching Hospital. Six mares in south-central Kansas were exposed to three infected stallions in Indiana, but none were confirmed to have contracted the disease.

CEM is a sexually transmitted, exotic disease of horses caused by the bacterium Taylorella equigenitalis. According to the U.S. Department of Agriculture Animal and Plant Health Inspection Service (APHIS), the first case of CEM ever diagnosed was in England in 1977. The first case confirmed in the United States was in March, 1978. The disease is considered a foreign animal disease and although it has been eradicated more than once in the U.S., it has surfaced a few times since 1978.

According to an April 10 update by APHIS, 17 stallions and five mares in the United States have been confirmed as positive for T. equigenitalis by the USDA´s National Veterinary Services Laboratories. In addition, locations have been confirmed for 733 additional horses exposed to the bacterium. The 755 horses are located in 47 states. All positive horses, and all exposed horses that have been located, are currently under quarantine or hold order. Testing and treatment are being put into action.

There is no evidence that CEM affects people, according to APHIS K-State veterinarian Ferrer answered several questions about CEM.

•What should horse owners look for? There are no obvious external signs in stallions. Infected mares can experience temporary infertility. Mares with active inflammation present a thick mucoid vulvar discharge. Some mares may become carriers, and while they remain infective, they show no external signs.

•If a horse is treated successfully after contracting CEM, will it ever be sound to breed? Mares and stallions that have been successfully treated and certified CEM negative are sound to breed.

•How can owners who are sending mares off for breeding (in state or out of state) make sure they will not contract CEM? The disease was considered exotic in the United States. Therefore, the risk of contracting CEM after breeding to non-exposed stallions is thought to be low. There have been no reported cases of exposed or positive stallions in the state of Kansas. If breeding mares to previously infected or exposed stallions, proof of CEM negative status after treatment should be requested. Mare owners can contact the state veterinarian if they have questions about risks or state regulations for transport of mares from and to states where positive cases have been reported. Since CEM can be transmitted via artificial insemination, owners who are shipping cooled semen in for AI should take the same precautions. Isolating the mares for 21 days upon return to the farm or insemination, and keeping strict biosecurity practices can help prevent the potential spread of CEM and other diseases to other horses at the farm.

•Do stallion owners in Kansas need to be concerned about mares coming from out of state or even in state, for breeding? Once more, given that the disease was foreign, the risk of a stallion contracting CEM after breeding a non-exposed mare is thought to be low. Since no official reports of CEM-positive mares in Kansas have been issued, breeding to in-state mares should possess a low risk. Stallion owners should contact the state veterinarian if they have questions about risks or check on state regulations for transport of mares from and to states where positive cases have been reported. They are also encouraged to work with their veterinarians to implement biosecurity measurements that would prevent introduction or dissemination of CEM or any other disease.

States where horses have been confirmed to have CEM include Kentucky, Indiana, Texas, Wisconsin, and California, according to APHIS.

More information about CEM is available on the USDA-APHIS Web site http://www.aphis.usda.gov/newsroom/hot_issues/cem/.