Mysterious disease detected in Virginia

Four northern Virginia horses have exhibited cases of equineherpesvirus (EHV) myeloencephalopathy, a rare neurologic disease, according toTheHorse.com.

Three of the horses were euthanized, and a fourth is recovering.

EHV is a version of EHV type 1, known in respiratory form asrhinopneumonitis.

Veterinarians are on the lookout for other unusual symptoms.

Necropsies on the two horses submitted for testing have been inconclusive, says Joseph P. Garvin, DVM, laboratory director of the VirginiaDepartment of Agriculture and Consumer Services' Warrenton Regional AnimalHealth Laboratory. Tests results were also inconclusive at the NationalVeterinary Services Laboratory in Ames, Iowa. Yet scientists have ruled out other possibleneurologic diseases, including West Nile virus, equine encephalitis and Equineprotozoal myeloencephalitis.

Garvin explained that tests of the tissue are conclusive only ifEHV-1 is grown out from the tissue or its DNA is found through a sensitivelaboratory test. Further complicating matters, the virus might not be presentin the horses by the time of their deaths.

Usually horses with this disease will run a high fever prior todeveloping symptoms, but the horses had no fever, Garvin reports. However, eachdisplayed hindlimb ataxia, loss of control of their bladder, a flaccid tail,and they eventually went down.

The neurologic form of EHV-1 often is cured with supportive care,but once a horse is down, it's difficult to nurse it back, which is whyveterinarians elected to euthanize the horses.