Equine Herpesvirus

Last Modified: February 26, 2024
Brown horse in a field with pine trees behind.

Equine herpesvirus (EHV), also known as equine rhinopneumonitis, is a family of highly contagious viruses found in horses worldwide. Of the nine known herpesviruses, EHV-1, EHV-3, and EHV-4 pose the highest disease risk to U.S. horses. They do not pose a risk to people.

EHV-1 primarily causes upper respiratory disease and abortions/stillbirths in horses. In some cases, it causes a neurological disease called equine herpes myeloencephalopathy (EHM) that can be fatal. EHV-3 causes a venereal disease called coital exanthema. EHV-4 primarily causes respiratory disease in foals and abortion in mares but can also produce cases of EHM. EHV-infected horses that don't develop EHM generally recover with no side effects.

Report Signs of Animal Disease

Producers or owners who suspect an animal disease should contact their veterinarian to evaluate the animal or herd. Find an accredited veterinarian.

Animal health professionals (veterinarians; diagnostic laboratories; public health, zoo, or wildlife personnel; and others) report diagnosed or suspected cases of nationally listed reportable animal diseases to APHIS Area Veterinarians in Charge and to the State animal health official as applicable under State reporting regulations. 

Controlling Equine Herpesvirus