Additional horses at Parx Racing, in Bensalem, Pennsylvania, have tested positive for equine herpesvirus-1 (EHV-1), the Equine Disease Communication Center (EDCC) reported April 10.

The EDCC reported April 2 that a horse from the track had exhibited signs consistent with the neurologic form of EHV-1, equine herpesvirus myeloencephalopathy or EHM, and subsequently tested positive for the virus. The horse was treated in isolation at a New Jersey equine veterinary hospital before being euthanized.

Late on April 10, the EDCC said that additional horses had tested positive for the virus.

“As of Wednesday afternoon (April 6) there were three positive horses confirmed in the original exposed barn at Parx,” the EDCC statement read.  "Arrangements were underway to find isolation facilities to move the positive horses to, then start a 21- or 28-day monitoring period for clinical signs in the remaining exposed, asymptomatic horses