Officials with the Calgary Stampede are investigating the cirucumstances surrounding the death of a horse during the chuckwagon races on Saturday night, and that’s causing some to question the safety of animals during the Greatest Outdoor Show on Earth.

During Heat 6 of Saturday’s Rangeland Derby, a horse on Layne Bremner’s team appeared to make contact with another wagon.

Officials say the incident resulted with the three-year-old thoroughbred suffering a broken leg.

"We’re saddened to report that one of the horses on the team of Layne Bremner suffered a broken leg,” said Kurt Kadatz, Calgary Stampede director of communications on Saturday. “A veterinarian was on scene immediately and determined the horse had suffered a broken right hind leg and specifically a fractured cannon bone.”

The injury is considered to be fatal for the horse, so it needed to be euthanized.

The horse was healthy and uninjured prior to the race.

The incident is firing up protesters who are against chuckwagon races at the Stampede and want to bring the sport to an end.

The sport has resulted in the most deaths of horses of all the Stampede events. More than 50 horses have died in the past 20 years.

Officials have made many changes to the sport over the years in an attempt to make it safer for the animals and the riders.

After four horses died in a crash in 2010, the rules were drastically changed, dropping the number of outriders from four to two.

Veterinarians say they also conduct pre-race health checks and enforce mandatory days off for each horse in the team.

Animal safety advocates, however, say those measures aren’t yet enough to prevent all animal deaths.

“They like to play the emotional figure. They like to say we love our animals, but the facts are animals are dying regardless of what they are doing,” says Michael Alvarez-Toye, one activist. “The only way to stop this is to stop the chuckwagons once and for all.”

Officials with the Rangeland Derby ended up penalizing Bremner, giving him a no-time result for Saturday’s race, a five-second interference penalty, and a fine of $2,500.