A mare in Los Angeles County, Calif., has tested positive for a non-neurologic strain of equine herpesvirus-1 (EHV-1) after she displayed mild neurologic signs, according to a March 30 statement from the California Department of Food and Agriculture (CDFA). The mare is the fourth Southern California horse to test positive in connection with the HITS Horse Show in Thermal, Calif.

Previously, three geldings–two on one premises in Monterey County and one in San Diego County–tested positive for the non-neurologic strain of EHV-1 in mid- to late March after attending the final week of the HITS event (March 5-11).

The horse in Monterey County displayed hind limb ataxia (incoordination) and was confirmed positive on March 14, a previous DCFA statement said. The San Diego County horse also displayed hind limb ataxia, and he was confirmed EHV-1 positive on March 15, the organization noted. The second Monterey County horse displayed mild neurologic signs and was confirmed positive on March 23, a statement said.

The Monterey County horses remain under quarantine; however, the San Diego County horse has been released from quarantine after turning back two negative EHV-1 tests, the March 30 statement said