Boomer is Poncho's best pal. His eyes are swirly and he was black and white like Poncho is, but he is now tan. He is the leader of Boomer's pack, or "Boomerland". He has a plan to launch all cats into the sun, but all the frequent meetings between him and the other dogs regarding this topic have decided is for the catapult to be painted puce, as well as who goes into the catapult after cats.
Boomer is usually calm and unfazed by his best friend's mistakes, ego, and paranoia.
He is generally a good friend to Poncho, but can sometimes inflate his ego, much to Poncho's chagrin. He also berates Poncho, and, along with Gus, spearheads the efforts to make fun of Poncho.