Horses were badly mistreated in a lot of the early movies, especially westerns. In all the scenes where a cowboy or an Indian gets shot and his hores takes a nosedive it's because they used tripwires to make the horse fall.
I still think the ones in cities that have to pull people around are mistreated. The ones in New Orleans, I think they should quit that practice before statues are torn down.
That reminded me of the Seinfeld episode where Kramer is driving people around New York and feeds the horse beans that make him fart.