EHV1 confirmed in Wyoming |

EHV1 confirmed in Wyoming

A horse in Johnson County, Wyoming, was diagnosed with Equine Herpesvirus neurologic disease, or Equine Herpes Myeloencephalopathy through laboratory testing and reported to the Wyoming Livestock Board staff veterinarians on April 4. The horse has been quarantined to its premise with 19 other horses.

According to the office of Wyoming State Veterinarian Dr. Jim Logan, the horse attended college rodeo events on March 15-16 at the Cam-plex in Gillette and March 21-24 at the Goshen County Fairgrounds in Torrington. Dr. Thach Winslow, Wyoming assistant state veterinarian for field operations, said that any horses that were at these events should be considered potentially exposed, and owners should consider taking preventative measures, including close monitoring of the horses and checking their temperatures at least twice daily. If any of these horses show neurologic signs or fever, the owner needs to isolate them and contact his/her veterinarian for advice and treatment options.

Steve True, the director of the Wyoming Livestock Board, said nearly all horses are exposed to the virus or are latently carrying the virus.

“It’s been around in time memorial in equine,” he said. “It’s becoming more prevalent all the time due as much to the fact that our equine industries are mobile and extremely mobile this time of year and getting congregated in some tighter areas in buildings.”

Clinical signs of the disease are observable when the virus is reactivated due to stress in the form of over-exertion, strenuous exercise, long-distance transport or at weaning.

Affected horses can shed large amounts of the virus for up to three to four weeks, making the possibility for exposure to other horses high. Horses typically show symptoms in three to 14 days from exposure and can be contagious prior to demonstrating symptoms. A temperature of above 101.5 is one of the first signs, necessitating owners of potentially exposed horses to check temperatures twice per day.

EHV-1, which is the neurologic manifestation of the disease and the only one reportable to state veterinarian’s offices, while the respiratory and abortion forms are not reportable. Colorado State Veterinarian Dr. Keith Roehr said horse owners who followed veterinary inspection requirements were immediately notified of potential exposure.

“The equine disease communications center is a national communications tool and when we saw that outbreak and then saw Wyoming’s information, we were able to go back and look at our Certificates of Veterinary Inspection and find certificates written by seven different veterinarians on dozens of horses that were (in the two county locations),” Roehr said.

Roehr’s office then contacted the private practicing veterinarians to communicate the information to their clients. Stopping the movement of affected horses, he said, is key and horsemen following Colorado laws regarding veterinary inspection were able to be contacted immediately.

According to the Wyoming Livestock Board, horses with neurological disease caused by EHV1 infection can soon become uncoordinated and weak and have difficulty standing, urinating, and/or defecating. Often the rear limbs are more severely affected than the front. Signs of brain dysfunction may occur as well, including extreme lethargy and a coma-like state. The disease is contagious and can be spread by direct horse-to-horse contact; by contaminated hands, equipment, and/or tack; and, for a short time, through aerosol dissemination within the environment of the stall and stable. There has been a marked increase in the number of EHV1/EHM cases in the U.S. in recent years. In the last 30 days, cases have been reported at large horse facilities and events in several states including Idaho, Arizona, Nevada and California. Owners who plan on taking their horses to such facilities and events can help prevent spread of the disease by practicing proper biosecurity measures. This includes not sharing equipment such as water/feed buckets and tack. They should also isolate their horses if they suspect them of being sick, and not allow them to leave the premise until cleared by a veterinarian.​ ❖

— Gabel is an assistant editor and reporter for The Fence Post. She can be reached at or (970) 392-4410.


Start a dialogue, stay on topic and be civil.
If you don't follow the rules, your comment may be deleted.

User Legend: iconModerator iconTrusted User

Farming & Ranching

See more