YOu want to talk old horses... I have one that I got when I was 14 or 15. Doesn't have a molar in his head.  All he eats is grain and alfalfla pellets. My youngest son thinks the world of him and feeds him twice a day. Just a pile of bones. But he feels good. All the vets know him and ask about him. Wanted one to put him down and she wouldn't do it....