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

On March 4, 2020, an attending veterinarian in Hamilton County, Indiana, confirmed a case of equine herpesvirus myeloencephalopathy (EHM, the neurologic form of equine herpesvirus) at an area boarding facility. An additional 20 horses have been exposed to the sick horse, and all are now under an official quarantine, according to an Equine Disease Communication Center Report.

EHV 101

Equine herpesvirus (EHV-1) 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