California animal health officials have reported that the equine herpesvirus-1 (EHV-1) case total in Inyo County has risen to three. Meanwhile, just one horse remains in isolation in the Los Angeles County outbreak.

The California Department of Food and Agriculture (CDFA) said Dec. 7 that the Inyo County horses have tested positive for the neurotrophic strain of EHV-1. One horse exhibited mild neurologic signs of disease, while the other two have only had fevers.

“The affected horses are part of a wintering pack string of horses and mules on an isolated high-desert ranch,” the CDFA said. “These horses and mules have been placed under quarantine with no movement allowed in order to limit disease transmission.”

Meanwhile, at the Los Angeles Equestrian Center (LAEC), the CDFA said no additional febrile horses have been identified, and just one horse remains isolated.

“The positive horse in isolation continues to shed virus and we are anticipating a negative nasal swab soon,” the CDFA said. “The LAEC incident has had a total of 13 … confirmed cases, all of those caused by the non-neurotrophic strain EHV-1 virus. Enhanced biosecurity measures continue in all barns under quarantine and all horses’ temperatures continue to be monitored twice daily.”

The incidents in Inyo and Los Angeles counties appear to be unrelated.

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

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usual