California EHV-1: One New Premises, Five New Cases Confirmed

A statement on the California Department of Food and Agriculture (CDFA) website has confirmed four additional cases of neurologic equine herpesvirus-1 (EHV-1) on the index premises and one case on a premises in another county. The CDFA does not believe the two situations are related, the statement said.

On Jan. 24, four more horses on the Orange County premises tested positive, bringing the total number of confirmed cases on that farm to 15. Only one horse--the index case--has displayed neurologic signs and is reportedly recovering, the statement indicated. One horse was euthanized on Jan. 18 after becoming recumbent, however a necropsy led veterinarians to believe the recumbency was unrelated to the EHV-1, the report said.

Also on Jan. 24, a horse on a Riverside County farm tested positive for the neurologic form of EHV-1, the statement read. The horse reportedly exhibited hind limb incoordination and urine dribbling, became recumbent, and was subsequently euthanized.

"The premises is under quarantine and CDFA has initiated an epidemiologic investigation," the statement said. "At this time we are not aware of any links to the Orange County incident. Additional information will be posted as it becomes available."

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).

Myeloencephalopathy is characterized by fever, ataxia (incoordination), weakness or paralysis of the hind limbs, and incontinence. Should a horse with potential EHV-1 exposure display any of the aforementioned clinical signs, a veterinarian should be called to obtain samples and test for the disease. 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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