A 12-year-old Thoroughbred, ridden by one of Doug Irvine’s outriders, collapsed and died following the fourth heat of the chuckwagon races at the Calgary Stampede on July 12th.

Stampede spokeswoman, Bonni Clark, said the horse had been examined prior to the race and was deemed fit to compete, and that it had not been involved in a collision during the race. The attending veterinarian determined that the horse died immediately, apparently from natural causes. A necropsy was to be conducted in order to determine the exact cause of death.

Last year, one of Irvine’s chuckwagon horses had to be euthanized at the Medicine Hat Stampede when it sustained a stress fracture to its leg. It has also been reported that in 2010, a member of Irvine’s Calgary Stampede team died during a training session.

The death, including that of a steer who had to be euthanized after its neck was broken in a steer wrestling competition two days prior, added fuel to the fire for local animal rights groups, who held a planned protest against the chuckwagon racing and the rodeo events at the Calgary Stampede on July 13th and 14th.

Three horses died as the result of chuckwagon racing at the 2012 edition of the Stampede. Read more about last year’s catastrophe, here.