In the equine industry three simple letters, when said in order, can silent a room of horsemen, turn a showground into a ghost town, and send shockwaves through barns. They’re E, H, and V, and they stand for equine herpesvirus-1, a contagious equine virus that can cause serious neurologic problems in affected horses. Fortunately for owners, veterinarians and researchers are constantly working to learn more about the virus and how to keep horses safe.

At the 2013 American Association of Equine Practitioners’ Convention, held Dec. 7-11 in Nashville, Tenn., Lara Maxwell, DVM, PhD, Dipl. ACVCP, presented the results of some recent research that horse owners might find encouraging: One EHV-1 vaccine could have at least some protective properties against the neurologic form of the virus.

EHV-1 is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (EHM, the neurologic form). Myeloencephalopathy is characterized by fever, ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, and incontinence.

Current vaccines are not labeled for use in preventing the neurologic form of EHV-1—only rhinopneumonitis and abortion—and clinical signs of EHM have been observed in well-vaccinated horses. Therefore, it’s remained unclear whether vaccination provides any protection against neurologic disease.

Maxwell, an associate professor of pharmacology at the Oklahoma State University (OSU) Center for Veterinary Health Sciences; Lyndi Gilliam, DVM, an associate prof