A toy og is a type of very small dog kept as a pet, as compared to a very small working dog, although both pet and working dogs can be very small. When an all-breed association or kennel club divides dog breeds into groups for purposes of competition, the Toy Group contains most of the smallest dog breeds in the club's registry. Allthough it is called a "Toy" dog the Chihuahua is the worlds smallest breed of dog.