There is at least one book about pet food. I haven't read "Food Pets Die For" yet, but I want to get it. I am interested in the health field. I know to stay away from corn which is a popular filler which is unhealthy for dogs, and the who-knows-what-it-really-is "byproducts". The first few ingredients should be meat. I have some Ultra now, our puppy was on it at the breeder. Its first ingredient is Chicken meal. I would know more about that if I read that book, but it probably is not as healthy as chicken. I believe that the healthiest choices are not found at Petsmart, but at specialty pet stores, or an animal feed store. I would like to make home made food, but life is so busy...
We have been using Innova. We tried several types of healthy food, and my dog did not like any of them. Maybe just like people food, the unhealthiest tastes the best.
We sprinkle just a tad of cheese on the food to get our dog to eat it. That's probably not the best either. It's probably not bad to keep changing foods as long as you do it slowly over time, to give her time to adjust to the changes.