The number of horses affected by the neurologic equine herpesvirus-1 (EHV-1) outbreak in the western United States and Canada continues to rise. Since health officials identified the virus as stemming from involvement with the National Cutting Horse Association (NCHA) Western National Championship competition, held April 28-May 8 in Ogden, Utah, the number of confirmed cases has reached the double digits.

Equine herpesvirus is highly contagious and can cause a variety of ailments in horses, including rhinopneumonitis (a respiratory disease mostly of young horses), abortion in broodmares, and myeloencephalopathy (evident in the neurologic form). The virus is not transmissible to humans. Clinical signs of the neurologic EHV-1 form include fever, ataxia (incoordination), weakness or paralysis of the hind limbs, and incontinence. The virus is generally passed from horse to horse via aerosol transmission (when affected animals sneeze/cough) and contact with nasal secretions.

State and provincial veterinarians are keeping close tabs on the number of confirmed and suspected EHV-1 cases. Since there is no centralized data reporting system, case counts are based on reports from individual states (although the Veterinary Infection Control Society has been collecting information regarding suspected and confirmed cases).

Utah State Veterinarian, Bruce L. King, DVM, said, "At this point we have had no confirmed cases of EHV-1 in Utah since the NCHA show that was held in Ogden. We do have some suspect horses that were at the show that laboratory confirmation is pending