The Wyoming Livestock Board had confirmed a case of equine herpesvirus myeloencephalopathy in Johnson County, according to the Equine Disease Communication Center.
The 15-year-old mare had onset of clinical signs on April 3. Her signs included hind end weakness. She was confirmed with equine herpesvirus type 1 (EHV-1 wild type) on April 4. The mare, which had been vaccinated, is still alive.
The mare has been isolated, and 19 of her herd mates have been placed under quarantine. It is not known where the mare contracted the disease, but she attended college rodeo events on March 15 and 16 at the Camplex in Gillette, Wyoming, and on March 21-24 at the Goshen County Fairgrounds in Torrington, Wyoming.
Any horses that were at those events should be considered potentially exposed, and owners should consider taking preventive measure that include twice daily monitoring of temperatures and close observation for neurologic or respiratory signs. Any horse with a fever or showing neurologic signs should be isolated immediately and a veterinarian contacted for advice and treatment options.