I would try the raw diet myself, at least as a supplement to other food. It's much more easily processed by dogs.

The prepared raw foods from pet stores are super-easy to feed. You keep it frozen, then take out what you'll need for the next day and let it defrost in the refrigerator overnight. I use a tupperware bowl with a lid for this. Then just serve it up the next day. It mixes in real well with canned food if you're skittish about feeding straight raw.

I know some folks that make their own raw food with raw chicken meat, hearts, and livers, and just run it thru a food processor. They get stuff real cheap from a butcher.