One PI and his dog
Understandable really as the demographic for this sort of book must be quite difficult. You're going to attract a reader who's into cats or hamsters, so presumably a fairly gentle type who likes animals, and the pet itself must be friendly unless it's attacking the bad guy in self-defence. A nice cozy murder is fine, but no Hannibal Lector. As a result they fail on two grounds. The animal is often not realistic enough, and usually wildly anthropomorphic while the crime is either boring, unbearably twee, or otherwise unbelievable.
However....I think I've finally found a series of novels that works brilliantly. The pet comes across as believable, and definitely a dog, in spite of some anthropomorphic tendencies. While the detective element is as nice a bit of gumshoery as you will meet with anywhere. Did I mention that the writing is brilliant too? Raymond Chandler eat your heart out. I'm referring to the excellent Chet and Bernie mystery series by Spencer Quinn ( Quinn more usually writes crime novels under his other name of Peter Abrahams. I haven't read any Abrahams yet, but will be doing so soon). The first in the series, Dog on it is a classy tale. Young Madison Chambliss goes missing, her estranged parents are at odds as to where she's gone. Mum is suspicious, Dad maintains that Maddie has done a runner. Bernie, the PI, is unsure who to believe; but when Chet the dog is dognapped, and Bernie himself later abducted, it soon becomes evident that Madison is at the centre of a nasty case of kidnapping.
The novel is told from the perspective of Chet, Bernie's crossbreed pooch. It is very funny. Dog life is brilliantly well observed; and there's a good, solid, and very well written mystery at the centre of the tale. You won't enjoy this if you're terrified of dogs; but if you're either keen on crime fiction or like dogs or just like something a little unusual you will love this. It was a complete joy to read from beginning to end. How refreshing to find a delightful new author with a different take on the crime novel.
Chet the dog has his own blog on all things dog : http://www.chetthedog.com/ and can also be followed on Facebook and Twitter. All of which I am now doing. But please read the novel first, it's so much more than just dog. A funny, engrossing read.