California EHV-1 Case Total Rises to Five

Two additional Orange County, Calif., horses have tested positive for the neurologic strain of equine herpesvirus-1 (EHV-1), according to a statement from the California Department of Food and Agriculture (CDFA). The two most recently confirmed cases brings the total case count in the current outbreak to five.

On Jan. 11 a gelding residing on a "large multidiscipline facility with no movement of horses on or off the property" tested positive for the debilitating virus. He was quarantined on the farm and is receiving veterinary care.

On Jan. 12 testing confirmed that two additional horses on the property were EHV-1-positive. Those horses were also isolated and quarantined on the same farm and are receiving veterinary attention.

Most recently, on Jan. 13, two additional horses on the premises tested positive for the virus. All affected horses are quarantined on the property, and additional horses residing on the premises are being monitored for signs of disease, the statement said.

No new cases were confirmed on Jan. 14 or 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).

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 updated information as it 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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