i have a 35+yr old quarter horse. he is fed mush twice a day. mixture of senior, beet pulp pellets, and alfalfa cubes. he has gotten to the point that he stands at the back gate and tries to get the chain off and let himself in. the other day he opened his stall (now i have to tie a rope around it to secure it) and helped himself to WAY to much food. then i sent his butt out. i came home and he had opened the gate and got into it again. this time only for 1/2 hour. the first time was several hours, don't know for sure, it was during the night. anyway, for the last three days he hasn't want to eat much when i have tried to feed him. he never leaves any left in the bucket and now he doesn't really touch much of it. his stool is very runny. looks like cow pies and it smells horrible. he is not showing signs of distress or rolling around or anything. help what can i do for him? he might have eatten beet pulp pellets dry! also he had a lot of sweet feed.