New EHV Cases Confirmed in Los Angeles County, California

New EHV Cases Confirmed in Los Angeles County, California

In many horses, fever is the only sign of EHV-1 infection, which can go undetected.

Photo: Peterson & Smith Equine Hospital

The California Department of Food and Agriculture (CDFA) reported Jan. 10 that a 12-year-old Quarter Horse mare displaying severe neurologic signs of disease has tested positive for non-neuropathogenic equine herpesvirus-1 (EHV-1).

“Due to the severity of clinical signs the horse was euthanized,” the CDFA said. “The premises of 56 exposed horses in Los Angeles County has been placed under quarantine and all horses are being monitored for clinical signs with twice daily temperature monitoring.”

Additionally, the CDFA said, a febrile 32-year-old horse residing on the index property tested positive for non-neuropathogenic EHV-1 on Jan. 10.

“This horse has been placed in isolation on site,” the agency said.

The CDFA said it has staff onsite that has begun an epidemiologic investigation.

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (the neurologic form). In many horses, fever is the only sign of EHV-1 infection, which can go undetected.

In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.

Horses with the neurologic form usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.

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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