Wyoming Herpesvirus Outbreak

An equine herpesvirus type 1 (EHV-1) outbreak has affected nearly 50 horses and caused the deaths of seven horses in Wyoming. The outbreak occurred at Paradise Ranch in Johnson County near Buffalo.

There are about 170 horses on the premises during the summer, says Jim Logan, DVM, Wyoming State Veterinarian. No one knows how the virus arrived, but it could have been brought in by one of the ranch's many leased horses.

Clinical signs of EHV-1 include staggering, rear leg weakness, dribbling of urine and, in serious cases, recumbency as the result of paralysis, then death. The virus can also cause upper respiratory problems and cause pregnant mares to abort. It is spread by direct contact. The ranch's first cases showed up in early July.

"We think we have the problem contained even though the disease hasn't yet run its course," Logan said in late July. "Travel restrictions are in place." The ranch is quarantined until at least three weeks after the last clinical case is diagnosed, treated, and resolved.

The ranch abuts public land, and the forest service has established restrictions concerning trail use. The trails used by the dude ranch are not readily accessible by the general public, thus minimizing the chance of horse-to-horse contact.

Logan stresses that this is not a rare virus. "The virus is endemic throughout the U.S. Often it is in a latent form in the horse's system and is activated as the result of stress. Nobody really knows why it crops up under some situations and not under others."

About the Author

Les Sellnow

Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.

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