There are quite a few threads on foods for our little pets. There are a variety of choices and opinions on whats best, from home cooking, to certain brands of excellent food, to home cooking even vegetarian diets. It can be quite a touchy topic, lol. Have you spoken to your vet for his recommendation yet? I'd pour over the threads that already exist and then you may have a better idea of what you are looking for
Good luck!! This turned out to be a particularly difficult thing to figure out.
The threads I'm referring to are in the Yorkie Health and Diet Forums