A Fistful of Collars: A Chet and Bernie Mystery by Spencer Quinn
I love this series. There's enough mystery to keep the plot moving along and enough comedy to make me laugh out loud. Bernie is a PI, and Chet is his canine partner.
The books are told from Chet's point of view. Quinn does "dog voice" better than any writer I've seen. Or maybe I just mean that he imagines a dog's thoughts pretty much the way I do!
Louise