Calder Race Course Dec. 3 placed a fourth barn under quarantine after a track veterinarian determined that a horse in the barn was showing neurologic signs of illness.

John Marshall, Calder vice president and general manager of racing, said the clinical signs were similar to those of a horse that became ill at Calder over the Nov. 28-29 weekend and tested positive for equine herpesvirus-1 (EHV-1). That unidentified horse was transported to the University of Florida College of Veterinary Medicine in Gainesville, Fla., where it was euthanized Nov. 30.

Calder on Nov. 30 placed the barn where the horse was stabled and two other barns under quarantine. Bill White, trainer of the euthanized horse, has horses in all three barns.

The expanded quarantine raises the number of horses under quarantine from 56 to 118. The Miami Gardens, Fla., track has about 1,800 horses in its stable area