Stephen

From Scrubs Wiki

Stephen is a stuffed dog, found by the Janitor, to replace Rowdy after Carla lost him. After J.D. and Turk found out, J.D. kept Stephen so they both could have a stuffed dog.

The two dogs are identical, except Rowdy is 48 inches from snout to tail and Stephen is only 46... "on a good day." J.D. can tell Stephen and Rowdy apart by feeling their undersides ("Don't ask me how").

The Janitor had to trade his squirrel army for him.