A Los Angeles County, California, horse is in quarantine after testing positive for equine herpesvirus-1 (EHV-1) earlier this month.

“A draft-cross gelding displaying neurologic signs has been confirmed positive for the non-neuropathogenic strain of equine herpesvirus-1,” the California Department of Food and Agriculture (CDFA) said in a Jan. 6 statement. “A small percentage of the non-neuropathogenic-infected horses can display neurologic signs compatible with equine herpes myeloencephalopathy which is a reportable disease in California. The positive horse has been quarantined and isolated.”

The CDFA said no horses have entered or left the affected premises since last September, and all exposed horses are being monitored. As of Jan. 15, no new cases had been reported.

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 myeloencephalopathy. In many horses, fever is the only sign of EHV-1 infection, which can go undetected