Wyoming State Fair shutters activities due to deadly equine virus 

GLENROCK (WNE) — EHV-1 has hit the Converse County community.

In a Dec. 1 Facebook post, the Wyoming State Fair announced that it would be cancelling all equine activities there  “out of an abundance of caution” due to the recent spread of the deadly virus.

EHV-1 is one of the most prominent forms of the Equine Herpesvirus, a disease with nine known versions. It affects the neurological system of the horse, causing many severe issues.

“Hind leg ataxia, weakness and lameness is usually the first symptom anybody sees,” said Dean Smylie, D.V.M. from Advanced Animal Care.

Another common symptom, Smylie said, is urinary incontinence, especially in mares, who are most affected.

According to Smylie, the best way to prevent horses from getting EHV-1 is to keep them away from the source.

While there is a vaccine for EHV, it protects more so against the respiratory form than it does to the neurologic. 

“There is some cross-protection for the neurologic form, but not much,” he said. “So vaccination is really not a viable option.” 

Owners who discover they have a horse that has been in contact with a carrier of the virus should isolate it to prevent further spread, Smylie said. 

Once a horse is diagnosed with the disease, in the absence of specific antiviral medications, veterinarians have to follow a symptomatic treatment approach.

“We just treat them symptomatically and hope that the horse can eventually build enough immunity to shed it,” he said. “It can be a pretty devastating disease. It can have up to a 40% mortality rate.” 

This story was published on Dec. 18, 2025.