Test results on the horse euthanized last week on a private Kent County, Md, farm confirm that the horse was infected with equine herpesvirus (EHV-1). One horse on the farm that was exhibiting neurologic signs appears to be improving and moving toward a full recovery. One additional horse, which had a fever, is now exhibiting neurologic signs and is being treated. Initial PCR tests on all clinically affected horses were positive for EHV-I.The farm received a horse from Pimlico Race Course Jan.10 before track officials closed movement to and from the facility. The farm is primarily a boarding and training operation for sport horses, not racehorses, and is not affiliated with any racetrack. The Maryland State Veterinarian placed a hold order on the farm Jan. 26. The order will remain in effect for 21 days after the onset of the most recent confirmed case. There has been no movement of horses on or off the farm. There are no other reported cases in any other off-track location in Maryland. EHV-I, which causes upper respiratory infection, can also cause neurological signs. Among the first signs of the illness are unexplained fever and mild to severe ataxia or unsteady balance. There is currently no known method to reliably prevent the neurologic form of EHV-1 infection. There is no reason to believe that there is any human health risk.Updates will be posted on the MDA website, www.mda.state.md.us. Additional research and veterinary information about EHV are also posted.