The Virginia Department of Agriculture and Consumer Services (VDACS) reported Aug. 17 that a third horse has tested positive for equine herpesvirus-1 (EHV-1).

On Aug. 15, the VDACS announced that its Animal Health Laboratory in Warrenton confirmed EHV-1 in two horses from Culpeper County. One horse is undergoing supportive therapy at the Marion duPont Scott Equine Medical Center (EMC) in Leesburg and the other was euthanized.

The infected horses originated from a small private farm in Culpeper County. That farm and all exposed horses residing there were placed under quarantine.

On the evening of Aug. 16, a third horse on the quarantined farm developed a fever and subsequently tested positive for the neurologic strain of EHV-1, the VDACS said. The horse is under a veterinarian’s care and has not exhibited any other signs of disease.

As a result of the new positive case, the farm’s quarantine will be extended until at least Sept. 6.

[brightcove videoid="3027535698001" title="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 equine herpes myeloencephalopathy, the neurologic form of the virus. 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.