Racing and training at Charles Town Races was suspended through Thursday after a sick four-year-old filly exhibited signs of equine herpesvirus (EHV-1).

The track received test results on Wednesday, which came back negative for EHV-1.

The barn where the filly was stabled was placed under quarantine on Monday after being examined by the track’s veterinarian. The quarantine was lifted following the negative test result.

Racing was canceled for Wednesday and Thursday.

Equine herpes is an airborne virus that affects the respiratory system in horses and can cause neurological damage. There is no known health threat to humans.