Collects Groo the Wanderer (1985-1995 Marvel) #29-32. Written by Sergio Aragones and Mark Evanier. Art by Sergio Aragones. Out of print.
From the publisher:
The first appearances of Rufferto, Groo's loyal dog! When the palace dog runs away to seek adventure, he encounters -- and becomes enamored with -- the world's least intelligent barbarian, Groo! Rufferto thinks he has found a companion for life, but Groo just thinks he's found dinner. And when a reward is offered for Rufferto, our heroes become hunted by, well, just about everyone. What's a dumb wanderer and an only slightly smarter dog to do?