More information on this disease and its status in Washington can be found at:

PULLMAN, Wash. — The College of Veterinary Medicine at Washington State University has confirmed one more horse with equine herpes virus or EHV-1. This brings the total number of horses now under isolation and care for the neurotropic form of the viral disease at the university’s veterinary hospital to three.

Confirmation of the third case came Wednesday, May 25, when nasal swabs administered to the horse, which is an inpatient in the WSU Veterinary Teaching Hospital, tested positive for EHV-1. The horse had been running a fever, but had not tested positive for the disease until today. Veterinarians said the case fits a common pattern for the development of the disease.
The total number of horses confirmed to have EHV-1 in Washington state now stands at seven, with no deaths. The ailing horses are located in Spokane, Thurston, Chelan and Asotin counties with one horse in each. Whitman County now has three, according to the Washington State Department of Agriculture.
This new confirmation at WSU means the restrictions for new, non-emergency horse or camelid patients coming to WSU’s Veterinary Teaching Hospital will be in place for a minimum of 21 more days. 
Emergency services are still available but owners must call ahead first to ensure the hospital can make special accommodations to protect any incoming animals. The phone number is 509-335-7073.