The Equine Disease Communication Center (EDCC) reported Jan. 31 that an Idaho horse has tested positive for equine herpesvirus-1 (EHV-1).

“The Idaho State Department of Idaho confirmed equine herpesvirus myeloencephalitis (EHM) in a Quarter Horse mare that exhibited ataxia, diminished tail tone, and urine dribbling at a private facility in Jerome County,” the EDCC stated. “The mare, which was previously vaccinated, was euthanized. Twenty-five horses out of 60 at the facility have been exposed and all 60 are isolated in quarantine.”

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 (the neurologic form). 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