New Case of Non-Neurologic EHV-1 Confirmed in California

New Case of Non-Neurologic EHV-1 Confirmed in California

Photo: Stephanie L. Church, Editor-in-Chief

A mare in Los Angeles County, Calif., has tested positive for a non-neurologic strain of equine herpesvirus-1 (EHV-1) after she displayed mild neurologic signs, according to a March 30 statement from the California Department of Food and Agriculture (CDFA). The mare is the fourth Southern California horse to test positive in connection with the HITS Horse Show in Thermal, Calif.

Previously, three geldings--two on one premises in Monterey County and one in San Diego County--tested positive for the non-neurologic strain of EHV-1 in mid- to late March after attending the final week of the HITS event (March 5-11).

The horse in Monterey County displayed hind limb ataxia (incoordination) and was confirmed positive on March 14, a previous DCFA statement said. The San Diego County horse also displayed hind limb ataxia, and he was confirmed EHV-1 positive on March 15, the organization noted. The second Monterey County horse displayed mild neurologic signs and was confirmed positive on March 23, a statement said.

The Monterey County horses remain under quarantine; however, the San Diego County horse has been released from quarantine after turning back two negative EHV-1 tests, the March 30 statement said.

The most recently confirmed mare is currently quarantined and under veterinary care, the CDFA statement said.

"Epidemiologic investigation indicates this horse may be a secondary exposure to horses from this facility that attended the HITS Thermal Horse Show," the organization relayed. "The CDFA continues to monitor the situation."

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 in California) is responsible for the more common respiratory EHV-1 cases," the CDFA said in a previous 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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