How is Lennie compared to an animal?

To a bear, a horse, a mouse and a dog. 'Dragging his feet a little, the way a bear drags his paws'. 'Drank with long gulps, snorting into the water like a horse'. 'Slowly, like a terrier who doen't want to bring a ball to its master, Lennie apporached, drew back, approached again'. 'They'll tie ya up with a collar, like a dog'.