Equine herpesvirus-1 (EHV-1) is relatively widespread in horses; approximately 60 percent of healthy horses harbor the virus. While the more common form of EHV-1 can cause respiratory illness as well as abortion, it is rarely fatal. However, a neurological strain of this virus, also known as equine herpes myeloencephalopathy (EHM), can kill 30 to 50 percent of affected horses. That's why it is critical for the California Animal Health & Food Safety Laboratory to be able to use PCR testing to differentiate between strains.
