Mac appeared in the Muppet special Dog City (aired as part of The Jim Henson Hour episde 104). Mac serves as a waiter at the Dog House, the bar-restaurant inherited by Ace Yu.
As the special slowly approaches its climax, Mac (cleaning up the bar) claims that he talked to the script writer and knows how it will end, including Ace's death and Colleen running off with a duck. Rowlf ignores him, however, noting that his mother always told him to "let sweeping dogs lie."
In his first scene in the special, taking orders at the Dog House, Mac is played by Steve Whitmire (though a different performer's voice is heard in the later sweeping scene).