On Oct. 17, the California Department of Food and Agriculture (CDFA) confirmed that one horse in Alameda County tested positive for the neurologic form of equine herpesvirus (EHV-1), also known as equine herpesvirus myeloencephalopathy (EHM). | Photo: Wikimedia Commons

The affected 12-year-old Arabian mare developed clinical signs of ataxia (incoordination), fever, and recumbency (down and unable to rise) on Oct. 16. She was reported as having been vaccinated and, after being isolated and quarantined, is currently under veterinary care. She had no history of travel from her home premises, and the case is stated as not related to the three Shasta County cases and one Sonoma County case confirmed in early October. One of those four horses resided at the index case’s premises, and the other three participated in a Sept. 27-28 event at Rolling Hills Equestrian Center, in Corning, California.

CDFA continues to investigate to identify potentially exposed horses and will provide updates as available.

EHV 101

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and EHM