On July 5, the California Department of Food and Agriculture confirmed that after displaying severe neurological signs, a Quarter Horse mare in Contra Costa County tested positive for the neurological form of the equine herpes virus.

Due to the severity of the clinical signs, the mare was euthanized. Initial investigation indicated that there were no additional exposed horses as the mare was the sole horse on a pasture with cattle. While the CDFA plans to continue monitoring for EHV-1, there have been no other reports of the disease and no event cancellations.

The CDFA issued a reminder to horse owners to practice proper biosecurity measures when attending an equine event, including limiting horse-to-horse contact, avoiding communal water sources, avoiding sharing of equipment unless thoroughly disinfected between uses, and monitoring animals for clinical signs of the disease, including a temperature of more than 102 degrees.