The owner might want to have the horse's teeth done if they haven't been recently. I have an old mare who will choke when her teeth start to get a few edges. She stops chewing well enough and thus, chokes. Float her and she's fine. We had a appy gelding with the worst parrot mouth I've ever seen. He choked regularly for the much the same reason. His bite was so screwed up he could never chew very well.