As a catch-all for Dog Breeds whose original purpose was to perform tasks that do not fit into a more specific category of work; most Working Breeds are robust, intelligent and headstrong, often unsuitable for novice owners. Made up of guardians of livestock and property, police dogs, sled dogs and rescue dogs, these workers come in all shapes and sizes, from the Standard Schnauzer to the Great Dane. But for the most part, these are Large, powerful Dogs. Without the right training, some working dogs can be difficult to handle, even dangerous. Very bright and rather determined breeds such as Rottweilers, Dobermans and Akitas have become extremely popular.