Animal rights activists are calling for an investigation after two horses have been euthanized after they were injured during chuck wagon races at Canada's biggest rodeo.

Animal Justice condemned what it called "inhumane rodeo practices" at the Calgary Stampede. It says chuck wagon racing is so dangerous that more than 50 horses have died in the event at the Stampede since 1986.

The Stampede's Chuckwagon Safety Commission said Wednesday that a horse was hurt in a collision between two rigs Monday night and was euthanized after a veterinary consultation with its owner.

A horse was also euthanized Saturday night after breaking a leg during the chuck wagon races.

Animal rights groups have long called for an end to the horse races.