Mad Dog is usually the brains and Dumptruck is the muscle when it comes to doing dirty work for Karnage. Karnage usually beats Mad Dog when he is angry. Mad Dog is something of a coward and he will do whatever his boss tells him to do, like in "Polly Wants A Treasure" when he tortured Kit Cloudkicker, to get Baloo and Ignatz the Parrot's attention. He is a mean, arrogant, determined, defiant, obnoxious, grouchy, menacing, annoying, dishonest, dramatic, obedient and gluttonous dog.
His voice actor is Charlie Adler.
He wears a purple vest, a pair of spiky wrist-collars, and a white hat with a pair of goggles.