CHEYENNE, Wyo. -- A horse at the Cheyenne Frontier Days Rodeo had to be euthanized after it was injured during a saddle bronc riding event.

The horse named Check Mate suffered a back injury during Sunday's event.

Video of the event posted by the animal protection group SHARK (SHowing Animals Respect and Kindness) showed the horse bucked its rider off and continued to buck. The third time the horse's legs touched the ground, the horse's legs appeared to slide under the animal and the horse collapsed on the ground.

Rodeo spokesman Bob Budd said the horse was sedated in the rodeo ring and moved by animal ambulance.

The horse was euthanized after a veterinarian determined the injuries were serious, Budd said.

SHARK officials said another horse died in 2009 after the rookie saddle bronc event at Cheyenne Frontier Days and that another horse was injured that year, but promoters refused to say what happened to her.

Cheyenne Frontier Days has an official news release on its website listing its animal care facts. It says CFD follows a set of 60 very strict guidelines on animal welfare set by the Professional Rodeo Cowboys Association.