Just a bit of a cultural "heads up" about rodeos... Although they are also in Canada, and probably Australia and other places with cattle and horses, every one I've ever been into in the U.S. has a fair bit of patriotic pagentry combined with the competition. Lots of flag waiving and "God Bless America" stuff, which I presonally enjoy and usually get all teary eyed about, but could seem a bit strange to folks from elsewhere. Like going to a friend's church of another denomination. Nothing intimidating or too over the top...just another slice of the American pie.
As for the animals...as noted above, they are well cared for. Most are pretty expensive, especially to feed. The bucking animals are bred specifically for it by rodeo stock operations and are their livelyhood so they can't abuse them. Spikes would likely lead to infections and sick animals are not so lively making for poor action. As for the bucking horses...they're pretty inteligent and I suspect it's as much sport for them as the riders. They know the drill.
Here's a link to one stock provider & rodeo producer's page weare they discuss animal treatment. Of course there are other sites for people opposed to using animals...for anything.
Personally I like the practical aspects of calf roping and the teamwork between horse and cowboy/girl. Even the bucking horses. But bull riding just doesn't seem to have much world application at all.
Definitely see a rodeo. Especially if in the evening, under the lights, after a warm day. It's a great experience.