I had a discussion about commercial pet food with Lady's specialist about a year ago. He said that the rise in pet diabetes in recent years can be blamed on commercial diets. Most are too high in carbohydrates because they are cheaper than meats. Dogs and especially cats aren't able to break down carbs the way humans can and carbohydrates convert to glucose (sugar) in the body. He said that Natures Variety Prairie was one of the few commercial diets he would recommend.
The brands you find in the grocery store are the worst as they are made with the waste from the human food industry, the "not fit for human consumption" by-products. In fact, the major brands are owned by well known companies like Del Monte, Proctor &Gamble and Colgate Palmolive. This article is a must read for anyone with a pet:
Get The Facts
Raw and homemade diets are wonderful as long as your consult your vet and/or a nutritionist to make sure they are appropriate for your dog. Raw, for instance, should only be feed to healthy dogs. Lady can't have it since she is diabetic and her weakened immune system can't handle the bacteria that is normally found in raw. Dogs with liver disease should not be fed raw either according to Dr. Dodds. Homecooked is great as long as you follow a carefully prepared diet developed by a nutritionist which contains the proper supplements to add. Dogs have a much higher calcium requirement than humans. The calcium/phosphorus ratio needs to be correct or your dog could get rickets, have heart irregularities and neurological problems.