Equine Herpesvirus (EHV)

General Disease Information
EHV-1 is not transmissible to people; it can be a serious equine disease that can cause respiratory and neurological clinical signs; it can even result in death. The most common way for EHV-1 to spread is by direct horse-to-horse contact. It can also be spread by contaminated tack, equipment, and people’s clothing. In addition, the virus can b e spread through aerosols (airborne) for a limited distance.

Symptoms include fever, decreased coordination, nasal discharge, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy, and the inability to rise. While there is no cure, the symptoms of the disease may be treatable. Horse owners should isolate any sick horses and immediately contact their veterinarian. Any individual horse with clinical signs consistent with neurological EHV-1 infection should be removed immediately from the area and placed in a separate enclosure for isolation.

The American Association of Equine Practitioners (AAEP) has developed resources about EHV-1, including FAQs.

Veterinarians are urged to contact their state veterinarian or state/provincial animal health department to report suspect cases of EHV-1.

Below are some messages you can use when talking to clients about EHV-1:

  • Equine herpesvirus myeloencephalopathy (EHM) is caused by equine herpesvirus-1 (EHV-1). The virus most commonly causes respiratory infection, and not all infected horses will develop EHM;
  • EHV-1 is a normally occurring virus found in the equine population; this outbreak is not being caused by a new virus or a new strain of a virus;
  • Signs of EHM in horses may include nasal discharge, incoordination, weakness of the rear limbs and hind end, lethargy, urine dribbling, and decreased tail tone;
  • Llamas and alpacas can also be infected with EHV-1 and may develop neurologic disease;
  • Currently, there is no equine vaccine that has a label claim for protection against EHM;
  • There is no specific treatment that has been proven effective for EHM;
  • If your horse has potentially been exposed to an infected horse (or through contact with people or equipment that have been in contact with an infected horse), or is showing signs that could indicate EHM, quarantine your horse and other potentially exposed horses and contact your veterinarian.


Colorado Department of Agriculture

New Travel Requirements for Horses Entering Colorado
Standard requirements for horses entering Colorado include a health certificate issued within 30 days of their arrival and a negative Coggins test within 12 months. The new requirement consists of a permit to enter the state. Horse owners who wish to bring their horse into Colorado must first call their veterinarian. That veterinarian can then contact the Colorado Department of Agriculture’s State Veterinarian’s Office at 303.239.4161 and request a permit number. That number would then be included on the health certificate.

Travel Tips for Horse Owners Traveling To or From Colorado:
1. Contact the State Veterinarian’s Office of the destination state to find out if travel requirements have changed for that state.
2. Call event organizers to see if they have new health requirements or if an event has been cancelled.
3. If traveling, practice appropriate biosecurity measures. Biosecurity tips may be found at www.colorado.gov/ag.
4. Isolate any new animals and those returning to the home premises for three weeks when possible.
5. Use separate water, feed supplies, and equipment.
6. Monitor the CDA webpage at www.colorado.gov/ag for further information to aid in the decision making for transporting horses.

 Additional Resources: