On Nov. 19, California Department of Food and Agriculture (CDFA) officials confirmed that one of the febrile horses that tested positive for equine herpesvirus-1 (EHV-1) on the San Bernardino County index premises — a 24-year-old Quarter Horse mare — developed severe neurologic signs and was euthanized on Nov. 16.

The updated report of Nov. 19 regarding the equine herpesvirus-1 outbreak in San Bernardino County stated that two additional febrile horses, an 11-year-old Paint mare and a 22-year-old Paint mare, were also confirmed positive for EHV-1.

The first (index) horse affected, a 13-year-old Quarter Horse mare, began showing clinical signs on Oct. 29 and was euthanized that day due to the severity of her clinical signs. She was confirmed positive upon necropsy on Nov. 5. CDFA quarantined 20 additional horses and enacted enhanced biosecurity measure, including twice-daily temperature monitoring.

The second deceased horse, a 22-year-old Paint gelding, was also euthanized due to the severity of his clinical signs. At that time, three additional horses on the premises with fevers exceeding 101.5° Fahrenheit were also confirmed positive for EHV-1