Dangerous Equine Herpesvirus Discovered in Colorado Horses
by Watch Staff
May 25, 2011 | 2843 views | 0 0 comments | 7 7 recommendations | email to a friend | print
Montrose, Ouray and San Miguel County Fairgrounds Temporarily Closed to Horses; Virus Not Transmissible to Humans

TRI-COUNTY AREA – In response to the recent outbreak of Equine Herpesvirus (EHV-1), the Montrose and San Miguel county fairgrounds have voluntarily closed their facilities to all horses for two weeks.

Horses are not boarded at the Ouray County Fairgrounds, but its facilities are closed to horses as well.

While those horses already boarding at the Montrose and San Miguel county fairgrounds may stay, horses that leave the premises cannot return until the restrictions are lifted.

All across the West, horse shows scheduled for May and June, including three at the Colorado State Fair, are now being rescheduled for late summer and early fall, due to the extremely contagious and potentially fatal nature of the disease. EHV-1 is not transmissible to humans.

According to San Miguel County Administrator Lynn Black, San Miguel Horseracing Association, Inc. will reschedule its horse races to mid-August.

Colorado State Fair General Manager Chris Wiseman reported: “We decided to reschedule [our] events to limit the number of horses traveling to and from our fairgrounds.

“Our horse shows are important to the Fair, and to Colorado as a whole, and we want to be proactive in protecting our horse community.”

The Zamora Roping show, originally scheduled for May 20-22, will be rescheduled; date pending.

The Mounted Shooting Regional, originally scheduled May 27-30, has been rescheduled for October 7-10.

The Sagebrush Slide Cow Horse Show, originally scheduled June 1-5, has been rescheduled for August 10-14.

There is no reason to believe any infected horses have been on the Montrose fairgrounds, according to Montrose County Public Information Officer Kristin Modrell. “This is strictly a precautionary measure for safety purposes,” she said, of the voluntary closing. “The state veterinarian is advising horse owners to keep their horses at home for two weeks. 

“By closing the fairgrounds, management believes they are helping to encourage that.” 

According to the Colorado Department of Agriculture, nine horses in the state have been diagnosed with EHV-1. Two horses were euthanized after showing severe neurological signs associated with the disease. Twenty-two horses have been identified as having been exposed, but tests have not yet confirmed they have the disease. The State of Colorado has issued 12 quarantine and hold orders for eight counties, including Bent, Boulder, Garfield, Gunnison, Mesa, Morgan and Weld.

Horses entering Colorado must apply for and receive a permit from the state veterinarian. Horses moving within the state must carry a veterinarian’s letter.

Outbreak Among Horses Attending Utah Event

The outbreak was first recognized in Colorado horses that had attended the National Cutting Horse Association’s Western National Championships, April 29-May 8, in Ogden, UT. Over 600 horses from around the West attended that show.

The Colorado Department of Agriculture encourages all horse owners who attended the Ogden event 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.

EHV-1 and Vaccines

The common vaccines available for EHV-1 immunization do not protect against the neurological form of EHV-1 disease, which is commonly called equine herpesvirus myeloencephalopathy (EHM); they do, however, protect against the respiratory and abortion forms of the disease.

The EHV-1 vaccines are believed to reduce the shedding of the virus and may decrease the amount of circulating virus in the system of infected horses, so vaccinations prior to infection may help reduce the severity of an outbreak. In the face of an EHV-1 outbreak, the value of vaccinating EHV-1 affected horses or exposed horses is questionable and may be detrimental to the horse. When an EHV-1 outbreak occurs, it may be helpful to give an EHV-1 booster immunization in a previously vaccinated, unexposed horse. Consult with your veterinarian to determine the best vaccination and treatment strategy for your horses in your particular situation.

For the latest up-to-date information, please visit the Colorado Department of Agriculture website at www.colorado.gov/ag.

General Disease Information

While EHV-1 is not transmissible to people, it can be a serious equine disease that can cause respiratory and neurological clinical signs and can 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. 

For more information, call Dr. Kate Anderson, 303/239-4161, Kate.Anderson@ag.state.co.us; or Dr. Carl Heckendorf, 303/239-4161, Carl.Heckendorf@ag.state.co.us.

Questions regarding the Montrose County Fairgrounds should be directed to Emily Sanchez at: 970/964-2180.
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