Some dogs are allergic or intolerant to certain ingredients in dog food. The dog is most often allergic to the protein source (soy, chicken, beef, or lamb) or carbohydrate source (corn or wheat). Occasionally, the dog may be allergic to other ingredients. Food intolerances commonly manifest themselves in gastric disturbances, diarrhea, and gas. Food allergies appear as skin and coat problems as well as other medical problems. If your rottweiler is allergic to food, your veterinarian can prescribe a hypoallergenic diet with a novel protein source. There are diets based on fish, venison, veal, turkey, or kangaroo meat with rice, potatoes, or barley.