CALGARY -- Three more chuckwagon horses were euthanized following the final night of racing at the Calgary Stampede and officials say they will initiate a 'thorough review process' on chuckwagon safety.

Stampede officials say the lead, right horse of Evan Salmond’s rig sustained a fractured left hind cannon bone during Heat 8 of Sunday’s Rangeland Derby.

Two other horses on the wagon sustained serious injuries as a result.

All three horses were immediately cared for by veterinary medical teams, but with no other option for treatment, all three were euthanized. 

In total, six horses have died at this year’s Rangeland Derby. 

Troy Dorchester’s 14-year-old gelding collapsed on the track during Heat 2 on Monday night. 

On Wednesday during Heat 2, one of Obrey Motowylo’s horses sustained a fractured left front radius and was euthanized on the track. 

The Stampede said both of the horses' deaths were unpreventable and common to horse racing. 

As for Salmond, he lost another horse this Stampede after his chuckwagon was squeezed into the inner rail of the track during Heat 7 of Thursday night’s race. Three other horses on Salmond’s team sustained minor injuries in that collision. 

An independent chuckwagon safety commission reviewed that race and determined that driver Chad Harden was at fault. 

Harden was handed a $10,000 fine and a disqualification from this year’s Stampede as well as all future Rangeland Derby competitions. He will have the opportunity to appeal that decision on September 1. 

For now, the Stampede says it will focus on what it calls a 'thorough review process' surrounding chuckwagon safety for next year. 

The details around that process are still not known, but Stampede CEO Warren Connell has asked for patience and understanding from the public. 

“We acknowledge that despite our best efforts to reduce risk, we’re dealing with animals and there is an element of unpredictability,” Connell said. 

“We review all of our practices and procedures including the dealings with the drivers and we’ll continue to do that.”