The state veterinarian has quarantined farms in two Virginia counties where a stallion infected mares with a highly contagious venereal disease.

Dr. Richard L. Wilkes placed full and partial quarantines on farms in Floyd County, in southwest Virginia, and in Goochland County, northwest of Richmond. Mares at these farms had contact with a Kentucky horse that has tested positive for contagious equine metritis.

A horse infected with CEM often suffers temporary infertility. Infected stallions usually do not show any symptoms. The disease has a 100 percent success rate for treatment.

The Virginia Department of Agriculture and Consumer Services said Tuesday officials are attempting to verify the location of another Virginia mare that may have been exposed.