Meat - Dogs and cats are natural carnivores, so it is important that the main source of protein in their diet is meat. Grains are inferior sources of protein and cats especially do not tolerate grains well. Diets with higher grain and carbohydrate content can lead to weight gain and other potential health problems.
Vegetables & Fruits - Vegetables and fruits contain beneficial vitamins and antioxidants and should be included in the diet as well -- to a greater extent for dogs than for cats. Cats are almost exclusively carnivores, so this portion should be smaller for them..