The Equine Disease Communication Center (EDCC) reported Feb. 17 that a horse from Chester County, Pennsylvania has tested positive for equine herpesvirus myeloencephalopathy (EHM), the neurologic form of equine herpesvirus-1 (EHV-1).

“On Feb. 16, 2018, the Pennsylvania Veterinary Laboratory, in Harrisburg, confirmed equine herpesvirus myeloencephalopathy in a horse with hind limb ataxia (which) tested positive for EHV-1 (A strain),” the EDCC said. “As of Feb. 17, the horse remains stable. The premises, a pleasure horse barn in Chester County, Pennsylvania, has been quarantined by the Pennsylvania Department of Agriculture, Bureau of Animal Health. All horses are being monitored for clinical signs of EHV-1 infection and biosecurity precautions have been implemented to prevent the spread of the virus off of the premises.”

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 (the neurologic form). In many horses, the 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