The Colorado Department of Agriculture continues to monitor the spread of Equine Herpesvirus (EHV-1) within the state.  

Disease Update as of 11am, 5/16/2010

  • 2 confirmed cases of equines with EHV-1.
  • 6 additional exposed horses are showing clinical signs of EVH-1.
  • Currently horses in four different counties (Boulder, Larimer, Mesa, and Weld) are being investigated for the disease and are under hold or quarantine orders.
  • One horse, which tested positive for EHV-1, was euthanized after showing severe neurological signs associated with the disease.  A second horse was euthanized with similar symptoms but test results have not been confirmed at this point.  The others are currently under treatment by veterinarians and in biosecure locations.
  • Both confirmed EHV-1 positive horses had recently attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah.  The Colorado Department of Agriculture is working with the Utah State Veterinarian to investigate the location as a point of interest for the infection.
  • This disease investigation is ongoing and constantly being updated.

What Can Horse Owners Do to Protect Their Horses?
If your horse attended the Ogden, Utah event:
CDA encourages all horse owners who attended the Ogden, UT, event should notify their veterinarian and isolate and monitor their horses for clinical signs of the disease. Individual horse and barn bio-security is very important.  Some horses may not show signs of the disease but may still be a carrier. Those owners are also encouraged to restrict movement of their horses.

Horse Movement
The Department also reminds horse owners to consider this disease risk before transporting horses.  Like any disease, EVH-1 can transfer from nose-to-nose contact. It can also be spread by contaminated tack, equipment, and people’s clothing. In addition, the virus can be spread through aerosols (airborne) for a limited distance. Continue to monitor our webpage for further information to aid in the decision making for transporting horses.

Disease Prevention
“This disease can have tremendous affects on the horse community and I encourage horse owners to be vigilant about the disease prevention methods they use within their premises,” said State Veterinarian, Dr. Keith Roehr.  “Colorado livestock owners have always been diligent about protecting the health of their animals and this is an important time to continue or implement proper biosecurity practices.”

Biosecurity and biocontainment control practices can reduce the risk of exposure to this disease. Key points of a biosecurity plan include isolating new animals and those returning to the home premises, supplying clean feed and water, implementing infection-control practices for visitors and personnel and avoiding movement from various locations Especially important is the isolation of any sick horses and making contact with your 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. Effective biosecurity practices lead to fewer health problems for animals and contribute to a longer and better-quality life.

For more information on equine biosecurity methods, visit <> .

General Disease Information
EHV-1 is not transmissible to people; it can be a serious equine disease that can cause respiratory, neurologic disease and death. The most common way for EHV-1 to spread is by direct horse-to-horse contact.  The virus can also spread through the air, contaminated equipment, clothing and hands.  

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.

The Department has received numerous calls from veterinarians, horse owners and media. To help facilitate a timely response, please see the following list.

  1. If you want to get your horse tested: contact your local veterinarian.
  2. If you are a horse owner and have questions about the disease, testing, or other aspects of the investigation:
    1. Contact your local veterinarian
    2. Dr. Kate Anderson, 303-239-4161, [email protected] 
    3. Dr. Carl Heckendorf, 303-239-4161, [email protected] 

Email comments or questions to [email protected]

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