Ever since cutting horses began showing symptoms of herpesvirus (EHV) following the National Cutting Horse Association Western National Championships in Ogden, UT, April 29-May 8, the horse world has been on edge. And for good reason. The number of confirmed or suspected cases grows daily as the virus spreads. States reporting confirmed or suspected cases as of May 18 include California, Colorado, Idaho, New Mexico, Utah, Washington, and Alberta and British Columbia, Canada.

The virus can have devastating effects on horses. The neurologic form of the disease, EHV-1, which is the type of current concern, can manifest itself as hind limb weakness, tremors, recumbency (leaning or lying down) or other types of nervous system symptoms that may be preceded by fever or respiratory signs. The disease, which isn’t transferrable to humans, is spread by close contact and can result in death of the infected animal. There is no specific treatment for EHV-1 and no equine vaccine has a label claim for protection against the neurologic strain of the virus, says William Moyer, president of the American Association of Equine Practitioners.

However, this isn’t the first outbreak of the disease in recent years; horsemen dealt with outbreaks in 2005 and 2006. What’s more it crops up almost yearly. For example, EHV is diagnosed nearly every year in South Dakota, says State Veterinarian Dustin Oedekoven.

“Strict adherence to the imposed movement restrictions and practicing good biosecurity procedures by the involved horse owners will be the key to limiting the scope of this situation,” says Dee Ellis, Texas state veterinarian.

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