There are several dietary modifications to consider when helping your dog fight a Mast Cell Tumor (MCT) diganosis. The first modification is to limit the intake of starchy carbohydrates that can potentially fuel the tumor. Some veterinarians recommend feeding foods that contain at least a 1.5 to 1 quality animal protein to carbohydrate ratio. Another dietary modification to consider is to limit the amount of histamines in your dog's food as histamines can aggrevate and swell the tumor. Also, as typical commercial pet food is loaded with lab-made ingredients, consider feeding a food that does not contain synthetic nutrients (the ingredients with the chemical-sounding names you probably don't recongize). Lastly, you can feed your dog foods that are high in anti-inflamatory ingredients like turmeric and ginger that can potentially limit tumor growth.