Pluto is Mickey Mouse's pet dog. Unlike Goofy, he is not an anthropomorphic dog. He is the only member of The Sensational Six that behaves like a "real" animal. Pluto, also called Pluto the Pup, was created in 1930 by Walt Disney Productions. He is a golden-colored, medium-sized, short-haired dog with black ears. Officially a mixed-breed dog, however, he made his debut as a bloodhound in the Mickey Mouse cartoon The Chain Gang.

Source: Mickey and Friends Wiki