Could be. McFarlane likes to modernize iconic characters; obviously Peter is Ralph Kramden/Fred Flintstone and maybe just a touch of Homer Simpson.
However, I've heard/read that Brian is a kind of representation of McFarlane himself. Maybe he let him take Snoopy's form and gave him his own personality? If you notice, McFarlane does Brian's voice, and it's pretty much just his regular voice.
Alex Reiger :[Trying to convince Louie not to antagonize Bobby] "It's not hard to make people feel bad about their lives. What's hard is making people feel good about their lives."