Five of seven horses residing on the Wright County, Minn., horse farm that recently confirmed three cases of neurologic equine herpesvirus-1 (EHV-1) infection have developed clinical signs consistent with the disease, according to a statement on the University of Minnesota (UM) Equine Center Facebook page.

"Three of these are being managed in isolation at the Large Animal Hospital, and their conditions are gradually improving," the statement, which was posted late Monday night (Nov. 19), reads. "To date no cases have been identified beyond the original farm but it will take an additional two weeks until this can be ruled out with confidence."

The current Minnesota outbreak began Nov. 10 when the index horse began showing signs of disease suddenly, treating clinician Anna Firshman, BVSc, PhD, CERP, Dipl. ACVIM, ACVSMR, assistant clinical professor of Large Animal Medicine at the UM Veterinary Medical Center, previously told TheHorse.com. That animal’s condition deteriorated rapidly, she said, and the decision was made to euthanize him.

Shortly thereafter, a second horse began to show clinical signs associated with EHV-1 and was admitted to the UM Large Animal Hospital on Nov. 11, Firshman said. Diagnostic tests soon confirmed EHV-1. The third horse began showing clinical signs not long after and was admitted to the hospital on Nov. 14, she relayed. That animal also tested positive for the disease. Both of these horses were in stable condition as of Nov. 16, Firshman said