Sixteen horses at one facility in King County, Washington, have now tested positive for equine herpesvirus-1 (EHV-1), seven of which have been euthanized.

On Dec. 15, the Equine Disease Communication Center (EDCC) first reported that a 13-year-old Haflinger gelding had tested positive for EHV-1. 

In a Dec. 26 update, the EDCC said subsequent testing had revealed additional EHV-1 positive horses.

“Thirty-seven of 60 horses (at the facility) have now been tested with 16 horses confirmed positive for the equine herpesvirus-1 neurotropic strain,” the EDCC said. “Seven horses have been euthanized due to equine herpesvirus myeloencepalopathy (EHM). Clinical signs of the EHM horses included 102-105°F fevers, hind-limb ataxia, no tail tone and dribbling urine. Treatment of horses include supportive care and anti-viral therapy