The Virginia Department of Agriculture and Consumer Services (VDACS) has confirmed a diagnosis of equine herpesvirus myeloencephalopathy (EHM) in two horses in Virginia.

On Feb. 27, the VDACS State Veterinarian’s Office confirmed that two horses exhibiting neurologic signs tested positive for equine herpesvirus-1 (EHV-1), EHM’s causative virus. Both horses were euthanized.

There is no link between the two horses and the timing of the EHM finding is coincidental. One horse was housed at the Hazelwild Equestrian Center, in Fredericksburg, and the second was located on a private farm in Powhatan County. Both facilities have been placed under quarantine. All exposed horses are being monitored twice daily for fever (temperature over 101.5°F) and other clinical signs, and the VDACS is working with the facility owners to determine if any exposed horses have left the premises. Owners of exposed horses will be notified and are advised to isolate and observe their horses closely for signs of the disease.

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 EHM. In many horses, the only sign of EHV-1 infection is fever, 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.