Animal health officials in California have confirmed that three additional horses tested positive for equine herpesvirus-1 (EHV-1) late last week. Those cases bring the total number of affected horses to five.

On Nov. 3, the California Department of Food and Agriculture (CDFA) reported that two Saddlebred horses in Los Angeles County had tested positive for non-neuropathogenic EHV-1. One of those horses was euthanized due to the severity of the clinical signs. The CDFA said those two horses, along with four others, recently returned from a horse show in Las Vegas, Nevada, that took place Oct. 27-29.

On Nov. 4, the CDFA issued an update indicating that three more horses at the same facility as the index cases had tested positive.

“Two of the three affected horses display neurologic signs and the third horse is febrile, and all three are in isolation,” the CDFA said. “Two of these newly confirmed equine cases attended the Las Vegas horse show last week.”

As of Nov. 6, no additional cases had been confirmed, the CDFA said. “Exposed horses on this premises continue to have their temperatures monitored twice daily and enhanced biosecurity measures remain in place. CDFA Animal Health Branch veterinarians continue to monitor the quarantine and situation on-site and will provide additional updates as they become available.”

[brightcove videoid="3027535698001" title="Health Alert: Equine Herpesvirus"]

Herpesvirus is highly contagious among horses and can cause a variety of ailm