Equine herpes concerns horse owners

Photo by Kathy Higgens

No kissing allowed — Horses at equestrienne events are spreading a deadly virus that causes neurological damage to horses.

An outbreak of Equine Herpes Myeloencephalopathy, a neurological form of Equine Herpes Virus, has local horse owners concerned. According to the California Department of Food and Agriculture, the virus is not transmissible to humans.

Twelve horses in California have been stricken with Equine Herpes Myeloencephalopathy (EHM). One horse in Kern County was euthanized.

All affected horses apparently contracted Equine Herpes Virus (EHV-1) after attending the National Cutting Horse Association’s Western National Championship in Odgen, Utah, on April 30 - May 8, 2011. As of this time, the California Department of Food and Agriculture has mandated that all horses showing signs of the virus, or that test positive for EHV-1, be quarantined.

“We have (more) suspected cases,” said Steve Lyle, California Department Food and Agriculture Public Affairs Director early last week.

Fifty-four exhibitors from around the state of California who participated in the Odgen, Utah event have been contacted and asked to isolate and monitor their horses.

“We’re not considering closing the (California) border at this time,” said Lyle.

As of May 23, there are 18 infected horses in 12 counties: Amador(1), Glenn(2), Kern(2), Los Angeles(1), Marin(1), Napa(1), Placer (3), Plumas(1), Sacramento (1), Shasta(1), Stanislaus(3), Ventura(1).

Although EHM can lead to death in horses, Equine Herpesvirus is not uncommon.

There was a similar outbreak in 2006-2007. Typically it might cause respiratory disease, abortions and less commonly, neurologic distress. The strain affecting the horses at the cutting horse event appears to be the more deadly, neurological form. The virus is frequently transmitted by aerosol discharge and close contact between horses, including shared tack, equipment and by human hands.

No vaccine is presently labeled as a preventive measure against EHV-1.

“There’s a modified live vaccine,” said Dr. William Gray of the Cottonwood Veterinary Clinic. “It’s a vaccine that they’ve had some success with.” But there is nothing officially on the market to prevent horses from contracting the virus, Gray stated.

As a precautionary measure, the National Cutting Horse Association cancelled all of its events for the weekend of May 20-22. Twenty-three equestrienne events were cancelled in California as well. Rancho Murieta, a popular equine facility located just south of Sacramento, has postponed and/or cancelled all of its events until June 7.

“We encourage owners to avoid any non-essential transport of their horses, mules and donkeys,” said Gary Magdesian, an equine veterinarian at UC Davis via a press release.

And if your horse has a runny nose and/or a fever, call a veterinarian immediately, advises both Gray and Lyle.