Officials at the California Department of Food and Agriculture (CDFA) confirmed on March 14 that a 14-year-old pony mare in Alameda County tested positive for equine herpesvirus-1 (EHV-1). On March 12 the mare presented with neurologic signs, including acute blindness, cranial nerve deficit, decreased tail and tongue tone, and hypermetria (a condition of cerebellar dysfunction in which voluntary muscular movements tend to result in the movement of bodily parts short of the intended goal). She’s reported as having been vaccinated and as affected and alive under quarantine at a veterinary hospital.

Forty-four additional horses were exposed and are quarantined at the home premises under enhanced biosecurity, including twice-daily temperature monitoring. All potentially exposed horses have been traced and owners contacted. Any horse that displays clinical signs or a temperature exceeding 101.5°F will be reported to the veterinarian for evaluation and potential blood and nasal swab sampling.