Following a particularly deadly series of accidents in 1986 where nine horses were killed in chuckwagon racing incidents alone – including five horses in one spectacular crash – humane society officials, fans and even some drivers called for major changes to the races, while others called for the sport to be banned entirely. Numerous rule changes were announced prior to the 1987 event. The Calgary chapter of the Society for the Prevention of Cruelty to Animals accepted the changes, stating it would not call for the sport to be banned given that Stampede officials had moved to improve animal safety, further changes were announced in 2011.