The California Department of Food and Agriculture confirmed a second horse positive for equine herpesvirus myeloencephalopathy (EHM), the neurologic form of equine herpesvirus-1 (EHV-1), on a San Bernardino County index premises. The 22-year-old Paint gelding was euthanized due to the severity of his clinical signs. Three additional horses on the premises having fevers exceeding 101.5 degrees Fahrenheit were also confirmed positive for EHV-1.

In addition to the index case, 20 horses were exposed on the premises.

EHV 101

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 EHM.

In many horses, the first or only sign of EHV-1 infection is fever, 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