The California Department of Food and Agriculture (CDFA) has released the quarantine put in place after one horse tested positive for equine herpesvirus-1 (EHV-1) earlier this month.
The quarantine was released on Jan. 25. No additional cases have been confirmed and the incident has been closed, the CDFA said in a statement.
The draft-cross gelding displayed neurologic signs and was confirmed positive for the non-neuropathogenic strain of EHV-1 in early January.
Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy. In many horses, fever is the only sign of EHV-1 infection, which can go undetected.
In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.
The virus is spread by direct horse-to-horse contact or through contact with objects contaminated with the virus.