In many horses, the only sign of EHV-1 infection is fever, which can go undetected. | Photo: Alexandra Beckstett/The Horse

The Equine Disease Communication Center (EDCC) reported May 3 that the South Dakota State Veterinarian has confirmed a case of equine herpesvirus myeloencephalopathy (EHM), the neurologic form of equine herpesvirus-1 (EHV-1), in a 19-year-old Quarter Horse mare exhibiting neurologic signs of disease.

“The horse belongs to a college rodeo participant and has extensive recent travel history to events within the Great Plains Region,” the EDCC said. “The horse has been isolated and voluntarily quarantined in Brookings, South Dakota, upon returning from an event in Hastings, Nebraska, the weekend of April 27-28. Owners of horses known to be directly exposed to the index horse are advised to restrict movement and monitor their horses for signs of illness, including twice daily temperature monitoring.”

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 only sign of EHV-1 infection is fever, which can go undetected