This article was updated at 4:30 p.m. on April 1 to reflect additional information obtained by The Horse.

The Maryland Department of Agriculture (MDA) reported March 31 that a horse from Pennsylvania that attended a Maryland horse show on March 15 has tested positive for the equine herpesvirus (EHV).

On April 1, the Pennsylvania Department of Agriculture told  The Horse  that "a quarantine was placed on a farm in the Dover area of York County. The quarantine will be effective for a minimum of 21 days as long as there are no further developments."

The MDA’s statement indicated that none of the other horses that attended the Maryland show and none of the horses that live with the sick horse in Pennsylvania are currently exhibiting any signs of illness. The MDA received a report of a horse that with a fever, but that animal tested negative for EHV on March 29.

The MDA statement indicated that the index horse did not exhibit any signs of disease until March 22 and did not exhibit any signs of illness while in Maryland. The officials of the Maryland show have contacted all trainers of horses in the division that the sick horse was shown in to alert them of the risk and recommend they monitor their horses through April 5, which marks the end of EHV’s 21-day incubation period.

The MDA’s Animal Health Program is monitoring the situation closely. Impacted owners should contact their private veterinarians to arrange for EHV testing if a horse exhibits significant temperature elevations or neurologic signs. Veterinarians are required to report equine neurologic syndrome to MDA