your answer depends on the dog. Purebred dogs are more "fussy" in the food department.
Dogs in the wild are not "purebred" to exact specifications. A wild dog/wolf can eat almost anything. Purebred dogs require a certain "finesse" in their food. Because they are purebred, alot of the natural resistance to allergies, disease and so forth is bred out. Allergies IS an issue in a purebred dog. A dog food rich in protein,
which is a wild animals main stay, and some vegetables, which wild dogs also eat, is ok.
The best way to find out is to try different foods and see which ones seem the best for your dog. A healthy dog will have clear eyes, a coat which is glossy and full, and a disposition that is both amiable and happy.
That may seem silly, but a healthy dog is a happy dog, and a dog with allergy problems to his food will NOT seem happy. They will have gas problems, and even dispostion problems if their food is not agreeing with them. Corn is probably not the best thing for them. Think of people: corn passes undigested in most of us. My dogs eat a diet with lamb and rice - made by Purina - and it suits them perfectly. I personally feel that rice is better for dogs than corn.