Marion County, Oregon, Horse Tests Positive for EHV

Marion County, Oregon, Horse Tests Positive for EHV

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

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

A horse from Marion County, Oregon, has been euthanized after testing positive for equine herpesvirus-1 (EHV-1).

The Equine Disease Communication Center (EDCC) reported that the horse began showing acute neurologic signs on March 18 and was referred to the Oregon State University College of Veterinary Medicine for veterinary care.

“The diagnosis was made on March 20 by a positive test for both the EVH-1 wild type and neurotropic genetic markers,” the EDCC said. “When horse’s condition deteriorated, it was euthanized.”

The horse’s home facility was quarantined and biosecurity measures have been implemented.

“A second location in Marion County with a high-risk contact horse has also been quarantined,” the EDCC reported. “Quarantined horses are being closely monitored and there is no indication at this time that the virus has spread to other horses beyond those being quarantined, and there are no traces to other states.”

Health Alert: Equine Herpesvirus

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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