The Unscratchables by Cornelius Kane

Here's one of those weird books that don't fit into any real category. It's a hard-boiled mystery peopled (ahem) entirely with cats and dogs. Intelligent ones. That wear clothes and carry guns and walk on their hind legs and wear shoes. No, I couldn't quite get my head around it either, but the book is surprisingly fun.

Max "Crusher" McNash is a detective bull terrier who doesn't like cats--especially not Siamese, after his experiences as a prisoner of war. But when a feral cat slashes and kills two rottweilers, then follows the murders up with the bloody murder of a guard dog, the chief of police has no choice but to call in the Feline Bureau of Investigation. Crusher is assigned to work with Cassius Lap, a Siamese whose delicate, pussy-footing attitude gets right up Crusher's nose. But Cassius soon turns up evidence of a conspiracy that goes far beyond a mere serial dog killer.

As I say, the book is fun. The author obviously had a blast inventing dog-and-cat stuff for his world. I had difficulty suspending my disbelief--I mean, dogs and cats just can't walk on their hind legs very comfortably, and they can't manipulate things like gun triggers very well with paws, and why would a dog need to wear shoes anyway? But if you can get past that, the mystery is pretty good, the characters are interesting, and the writing is solid.

B&N link