T he neurologic form of equine herpesvirus type 1 (EHV-1) has been diagnosed in at least five different states in January and February (The Horse learned of a fifth state with herpes after the cover went to press). While many of the cases were detected at racetracks, it is important to note that this not a disease limited to the racing industry–any horse facility can be affected by this illness. Using stringent biosecurity measures is the best way to help ensure that the virus does not emerge or spread at a facility or farm.

EHV-1 can cause respiratory or neurologic signs in all ages, breeds, and sexes of horses and abortion in pregnant mares. The neurologic form can debilitate the horse until it is unable to stand, and many times it must be euthanatized. Herpes can be spread through nose-to-nose contact by nasal secretions, but also via shared buckets, equipment, and handlers.

David Powell, BVSc, FRCVS, professor in veterinary science at the University of Kentucky’s Gluck Equine Research Center, described the clinical signs in the current outbreaks: “The initial feature is the animal developing a high fever, and one of the new features of this manifestation is that they very quickly become ataxic (incoordinated) or paralyzed in the hind legs. Usually they are incontinent. There is a very rapid progression of the disease to the extent that a number of animals have become recumbent (unable to rise) and unfortunately have been euthanized within two, three, or four days. This is something that hasn’t been observed before–the progression of the disease has previously been much slower than that.”

As of Feb. 7, The Horse had reported on several recent neurologic cases (see timeline at right). Scientists at the Gluck Center and other institutions continue to research EHV-1 and prevention (see www.TheHorse.com/ViewArticle.aspx?ID=6646). For more information see www.TheHorse.com/EHV