One additional horse has tested positive for a non-neurologic strain of equine herpesvirus-1 (EHV-1), according to a March 23 statement from the California Department of Food and Agriculture (CDFA). Two California geldings—one in Monterey County and one in San Diego County—previously tested positive for non-neurologic EHV-1, according to the CDFA.

The horse in Monterey County displayed hind limb ataxia (incoordination) and was confirmed positive on March 14, the statement said. The San Diego County horse also displayed hind limb ataxia. He was confirmed EHV-1 positive on March 15, the organization noted. Both horses are under veterinary care; however, no further information on their immediate conditions was available.

According to Friday’s statement from the CDFA, the most recently confirmed horse resides on the same premises as the previously diagnosed Monterey County horse, and recently began displaying "mild neurologic signs."

"All three confirmed horses participated in the HITS Thermal Horse Show March 5-11, 2012," the CDFA statement said. "The confirmed cases are quarantined and isolated, and enhanced biosecurity protocols have been implemented