In many horses, the first or only sign of EHV-1 infection is fever, which can go undetected. | Photo: Stephanie L. Church/The Horse

The positive horse, a 14-year-old Quarter Horse mare, began showing clinical signs of limb edema (fluid swelling), recumbency (down and unable to get up), urine dribbling, and poor tail tone on Oct. 27. She was subsequently euthanized.

Only the affected premises has been quarantined; statewide restrictions have not been enacted.

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 equine herpesvirus myeloencephalopathy (EHM, the neurologic form)