Equine Herpes Virus Type 1 (EHV-1) infection in horses can cause respiratory disease, abortion in mares, neonatal foal death, and/or neurologic disease. The neurologic form of the disease caused by EHV-1 is called Equine Herpes Virus Myeloencephalopathy (EHM).
Transmission likely occurs by inhaling infected droplets or ingesting material contaminated by nasal discharges or aborted fetuses. Clinical symptoms may include a fever, difficulty urinating, depression, and stumbling or weakness in the hind limbs. Supportive therapy is often used to treat these cases. In severe cases, horses will be unable to stand; these cases have a very poor prognosis. EHV-1 is not transmissible to humans.
April 2026: A gelding thoroughbred displayed clinical signs of Equine Herpes Virus Type 1(EHV-1) / Equine Herpesvirus Myeloencephalopathy (EHM), while at the HITS Commonwealth National USEF horse show in Culpeper County, Va. The horse has been euthanized and 42 horses at the show have been exposed and will quarantine for 21 days at the event site or their home farms. Additionally, 13 horses from the index home farm are also under quarantine. All owners of exposed horses have been notified. For more information on this detection, please visit https://equinediseasecc.org/alerts.
Horse Owners: If you suspect your horse has been exposed to EHV-1, contact your veterinarian. Exposure guidance includes:
- Exposed horses should be isolated for 21 days after last known exposure.
- Appropriate isolation includes restricted access to other horses, avoid sharing of equipment or personnel, and utilizing protective barrier precautions.
- Exposed horses should be monitored twice daily for elevated temperature (above 101.5°F), respiratory signs (nasal discharge, coughing), and clinical signs consistent with EHM (neurologic symptoms including inability to stand, difficulty walking, lethargy, and urine dribbling).
- If elevated temperature, respiratory signs, or EHM-compatible clinical signs are noticed, contact your veterinarian.
Equine Event Guidance: EHV-1 can be shed for prolonged periods of time, including in clinically healthy horses, which increases risk for continued disease spread during a EHV-1/EHM outbreak.
- Event organizers: Consult with your veterinarian to understand the risks associated with hosting equine events during a multi-state outbreak. Event cancellation or postponement may be important to stop disease spread. Events that do take place are recommended to use short-timed health certificates within 72 hours and practice increased biosecurity on site.
- Horse owners: Consult with your veterinarian to understand the risks associated with travel to upcoming equine events. EHV-1 is a ubiquitous virus and commonly present in the environment, so biosecurity measures are paramount to decreasing potential for disease transmission.
Veterinarians: If you have a horse with signs of acute neurologic disease, please contact the State Veterinarian’s Office at 804-786-2483. After hours, call 804-750-8845. We will provide guidance on isolation and testing. Diagnosis of EHV-1 can be difficult, as periods of viral shedding and viremia may vary - paired samples, including nasal swab and whole blood, is critical.
Interstate Movement: Please note that many states may be implementing movement restrictions or new import requirements for equines during this outbreak. Always check with the state of destination to ensure you are following import restrictions.
EHM Disease Information:
For questions or more information, call:
804-786-2483
Visit the Division of Animal and Food Industry Services directory.