Unacceptable to the AHA
I've always enjoyed this movie--one of my favorite Westerns--but I've just read in the trivia about how the reckless film making caused the death and injuries to some of the horses, and that leaches a good deal of the pleasure out of it for me.
By the time this movie was in production, major film studios had to know that that kind of treatment of animals was unnecessary and uncalled for. It's bad enough when production companies put animals in harms way out of ignorance or financial constraint; that's not an excuse, but at least it's understandable. But these people knew better and could afford to do things otherwise and chose to destroy creatures when it could have been done another way.