California Confirms Two Cases of Non-Neurologic EHV-1

Two geldings in California—one in Monterey County and one in San Diego County—have tested positive for a non-neurologic strain of equine herpesvirus-1 (EHV-1), according to a statement from the California Department of Food and Agriculture (CDFA). Published reports indicate that both horses recently attended the HITS Desert Horse Show in Thermal, Calif.

The horse in Monterey County displayed hind limb ataxia (incoordination) and was confirmed positive on March 14, the statement said.

"The positive horse has been quarantined and is under veterinary care," the statement said. "The CDFA has initiated an investigation, and owners of exposed horses are asked to take temperatures twice daily and monitor for clinical signs."

The San Diego County horse, which the CDFA reports "participated in the same large equine event" as the Monterey County horse, also displayed hind limb ataxia. He was confirmed EHV-1 positive on March 15, the statement noted.

Although it's not transmissible to humans, EHV-1 is highly contagious among horses and camelids, and it is generally passed from horse to horse via aerosol transmission (when affected animals sneeze/cough) and contact with nasal secretions. The disease can cause a variety of ailments in equines, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (EHM, the neurologic form).

"(The strain of virus confirmed this week) is responsible for the more common respiratory EHV-1 cases," the CDFA said in the statement. "A small percentage of non-neuropathogenic EHV-1 infected horses can display neurologic signs and are classified as equine herpes myeloencephalopathy cases, which is a reportable condition in California." will continue to provide updates as more information becomes available.

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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