I agree that he teeth should be checked, but just because food is falling from his mouth does not exactly mean that they have to have their teeth floated. My horse got stuck under a fence awhile ago and after she started dropping feed. We got her teeth checked and she was fine and didnt need to be floated. So we go a chiropracter out and we found out that she had thrown her poll out and because of that her jaw was crossed. She's getting regular adjustments and though much better than before her jaw is still crossed and she still drops feed. I find that until she 100%, when I wet her feed and make it into a mush, she has a much easier time eating and doesnt drop feed anymore.