In many horses, the first or only sign of EHV-1 infection is fever, which can go undetected. | Photo: Anne M. Eberhardt/The Horse

-On May 16, the Alcohol and Gaming Commission of Ontario (AGCO) confirmed two horses with the neurologic form of equine herpesvirus-1 (EHV-1) at Woodbine Racetrack in Ontario, Canada. Both horses, 2-year-old Thoroughbreds, resided in Barn 12 and were transported from the racetrack to the Ontario Veterinary College for testing and treatment on May 16, along with a third horse that subsequently tested negative.

Four other horses have been isolated. One resided near the two positive horses, and the three other horses have exhibited fever but no other clinical signs associated with EHV-1.

To determine possible spread of the disease to horses in other Woodbine barns, no horses will be allowed to exit the racetrack without AGCO approval until further notice; no horses will be allowed into or out of Barn 12 until further notice, including for training, except for emergency veterinary care or to be isolated; only essential people will be allowed in Barn 12; each horse stabled at Woodbine must have its temperatures monitored, recorded, and posted on its stall door for twice daily inspection; and only ponies housed in the same barn will be allowed to pony horses