Mutt has light-brown fur, dark brown ears, and a dark brown spot on his left eye. He will typically stick his head down a hole into the tunnels to announce when the pound has visitors.
Mutt appeared in the background of some early season 1 episodes, but the first time he was seen announcing someone's arrival was in "The General," when he informed Lucky that a messenger had arrived from Pound Puppy Headquarters with an important message.
Mutt's most recent appearance was in "The Road to Empawerment."
- The dark-brown spot on Mutt's left eye has had some inconsistencies. During one shot in "Mutternal Instincts", the spot was seen over his right eye. The spot was also on his right eye during his appearances in "Barlow" and "Hello Kitten."
- In "Kennel Kittens Return", a dog was seen announcing to Lucky that there was company in the alley. This dog was not Mutt, however, he had Mutt's voice.
- In "The Pups Who Loved Me", a Doberman (with Mutt's voice) was seen announcing Bondo's arrival.