Less than a week after a mare from Tuolumne County, Calif., tested positive for the neurologic strain of equine herpesvirus-1 (EHV-1), seven other horses residing on her home premises have tested positive for the virus, according to a statement from the California Department of Food and Agriculture (CDFA). Further, a second premises has been quarantined after two horses residing there tested positive for the virus.

"Seven of the eight horses displaying compatible clinical signs at the quarantined premises have been confirmed positive for neuropathogenic strain of EHV-1," the Sept. 15 statement read. "Five of the confirmed cases have displayed neurologic signs and two of the cases have only demonstrated a fever. One of the severely affected neurologic confirmed cases has been euthanized."

The statement also noted that the mare that initially tested positive on Sept. 12 made improvement at the referral hospital she was being treated at, and was returned to the quarantined premises, where she continues to recover.

Also on Sept. 15, the CDFA indicated that a second premises in San Joaquin County has been quarantined in relation to the Tuolumne County outbreak