Many dogs have food allergies and have trouble processing certain ingredients, which is why I'm a huge advocate of natural types of dog foods. Natural dog foods don't contain any artificial ingredients, preservatives or synthetic chemicals, which makes it easier for your dog to digest. Dog foods considered to be natural include brands, such as Blue Buffalo, Nature's Variety, Solid Gold, Wellness and Halo (just to name a few). Taking it a step further, there are many types of dry dog food that do not include ingredients such as corn, soy & wheat, since many dogs are allergic or have trouble digesting those ingredients. My dog (Dreyfuss) is allergic to those ingredients AND had dry skin, so I'm a huge fan of Solid Gold. He's been on this type of food for the past 4 years and he's uber healthy... Natural dog foods aren't very cheap, but they're well worth every penny in terms of keeping your dog healthy and happy.