You are not doing anything wrong with the type of food you choose to use. A Maltese is one of the breeds of dogs that is in the AKC Group called Toys. They include the smaller dogs like Papillons, the smallest of the 3 Poodles(Toy Poodle, it is called this to distinguish it from the Miniature and the Standard), Miniature Pinschers, Pekingese, Chihuahua, Yorkies etc. A Maltese is just a Maltese, not a Toy Maltese.