A Thoroughbred x Irish Draft Horse given up as "unridable" has calmed down after learning to play football (or soccer as you may know the game). Horse trainer, Emma Massingale, taught her horse, Kariba, to play football as a therapeutic game to expend some energy. Kariba will quite happily play with the 65cm inflatable ball all by himself if left alone, even figuring out how to bounce the ball out of a corner if it gets stuck.
Kariba has quite a repetoire of football specific behaviors including passing, shooting, dribbling and headers. Massingale says Kariba prefers to play in the midfield, but would be very hard to get a shot past if he played in the goal-keeper position.
Massingale also has this advice "establishing trust and co-operations is essential for a successful partnership". Massingale is based in Devon, England, but travelled to Australia to learn more about co-operative horse training and does not advocate force-based training methods.