The steer had difficulty standing following a run during the steer wrestling event Saturday and was later put down by on-site veterinarians.
"You never want to see something like this," said steer wrestler Casey Martin in a statement. "I run horned cattle on my ranch and I throw them down often to do medical and field doctoring. When I realized this steer was injured I held him still to prevent any further injury."
Event organizers said in a release the incident will be reviewed, although no post-mortem will be performed.