Good ones will have NO gluten and NO grains (this includes rice and corn), a good protein source (meat, fish, eggs, tofu, or poultry), green leafy vegetables, sweet potato, berries and some other fruit, fish
oil (containing DHA), vitamins, minerals, probiotics, and digestive enzymes.
The good food does not have to every single ingredient that I have listed, but will contain many of the ingredients.
Some good brands: Wellness Grain Free, Evo/Innova, Orijin canned only.