More than two weeks after the conclusion of the National Cutting Horse Association’s (NCHA) Western Regional Championships–held April 19-May 8 in Ogden, Utah–reports of equine herpesvirus-1 (EHV-1) confirmed cases continue to trickle in. The outbreak, believed to stem from horses that attended the NCHA competition, captured the collective attention of the horse industry last week after numerous facilities quarantined horses.

Equine herpesvirus-1 is highly contagious and can cause a variety of ailments in horses, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (the neurologic form). The virus is not transmissible to humans. Clinical signs of EHV-1 myeloencephalopathy (EHM) 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.

New Cases

California – One new case of confirmed EHV-1 had been reported in California as of noon today, according to the state’s Department of Food and Agriculture. This brings the total number of confirmed cases to 18. There is only one related fatality thus far in California. A statement released by the department indicated that "seven positive horses have displayed neurological signs, 10 cases have displayed an increased temperature, and one horse has not displayed any clinical signs." The horses are located in the following counties: Glenn, Plumas, and Shasta in Northern California; Amador, Marin, Napa, Placer, and Sacramento in North Central California; Stanislaus in Central California; Kern in South Central California; and Los Angeles and Ventura in Southern California