EHV-1 Update: Six Confirmed Cases of EHV-1 in Colorado Horses
Posted on Wed, May 18, 2011

UPDATE:  As of 5/18/2011, 1pm

6 confirmed cases of horses with EVH-1

  • Five of the confirmed EHV-1 positive horses had recently attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah.
  • One of the horses diagnosed with EHV-1 received the infection through contact with horses that attended the Utah event.
  • 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.
  • 14 suspect cases.  Suspect cases are those horses that are believed to have been exposed to EHV-1 but confirmatory tests are still pending.
  • 9 quarantine and hold orders have been issued in 4 counties (Boulder, Larimer, Mesa, & Weld)

UPDATE:  Camelids
Camelids, which are alpacas, llamas and camels, are susceptible to EHV-1.  There have been no cases of EHV-1 cases in camelids related to this spread and there are no travel restrictions.  The main animals at risk for EHV-1 are those horses that traveled to Ogden, UT.  Therefore, CDA believes camelids are low risk for this disease spread.

UPDATE:  Colorado State University Veterinary Teaching Hospital
The equine section at Colorado State University Veterinary Teaching Hospital (CSUVTH) is accepting emergency patients and is not and has not been under quarantine due to the outbreak of equine herpesvirus. The CSUVTH has remained open to emergency equine and camelid patients during the outbreak, as well as to all other animal patients. Horses brought into the hospital are routinely and carefully screened for symptoms and history of possible exposure to the disease. Any horse that may have been exposed to the virus is being held in a separate isolation unit away from the main equine section and other equine patients that are coming and going. The isolation unit where horses that may have been exposed to the disease are treated is specifically designed for treating infectious disease cases, such as EHV-1 cases. The unit is not physically connected to the main hospital or equine section of the hospital and horses in the main hospital are not exposed to horses in the isolation unit.


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.

Additional 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 organizers of the event to see if they have new health requirements or if it has been cancelled.
3.      If traveling, practice appropriate biosecurity measures.  Biosecurity tips may be found at
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.      Continue to monitor the CDA webpage at for further information to aid in the decision making for transporting horses.

If your horse attended the Ogden, Utah event:
CDA encourages all horse owners who attended the Ogden, UT, even to notify their veterinarian and isolate and monitor their horses for clinical signs of the disease. These horses should have their temperature taken twice a day. Horses with elevated temperature can be sampled by a veterinarian to analyze whether their horse is shedding EHV-1.  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.

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

1.      If veterinarians or horse owners have questions about the disease, testing, or other aspects of the investigation:

a.       Contact your local veterinarian
b.      Dr. Kate Anderson, 303-239-4161,
c.       Dr. Carl Heckendorf, 303-239-4161,

2.      If you are a media outlet and would like to set up an interview: contact Christi Lightcap, 303-239-4190,