There has been a series of new cases of equine herpes virus in California over the last several weeks, in Tuolumne, San Joaquin and Sonoma counties.
Equine Herpes Virus (EHV-1) infection in horses can cause respiratory disease, neurological disease, abortion in mares and neonatal foal death. The neurological form of the disease, is known as Equine Herpes Myeloencephalopathy (EHM). The neurological form of the virus has the potential to cause high morbidity and mortality. EHV-1 is easily spread and typically has an incubation period between 2-10 days. Respiratory shedding of the virus generally occurs for 7-10 days, but may persist longer in infected horses. For this reason, the isolation period recommendation for confirmed positive EHM cases is twenty-one (21) days
More information is available at: http://www.cdfa.ca.gov/ahfss/animal_health/equine_herpes_virus.html