Can you give more details to breed, age, height, weight, activity level, etc? It's hard to recommend something without knowing more information about him.
I've been feeding Nutrena SafeChoice and have been very pleased with it. I LOVE Nutrena's Senior formula and it's working wonders with my hard keeper.
I'm concerned about him eating dirt though. Do you use SandClear with him? I'd highly recommend it so he doesn't get sand colic.
"The greatest pleasure of a dog is that you may make a fool of yourself with
him and not only will he not scold you, but he will make a fool of himself too."