This is the second in Tamora Pierce’s excellent YA series about a fantastical keeper of the peace in the realm of Tortall.  You’ll have to venture into the YA shelves to find it.  Frankly, some of the best sf and fantasy adventure is there these days, by the way. 

This book is told through the journal entries of young, precocious Cooper, who has just earned her stripes to be a real dog (translate here as cop).   The language and world-building are lovely, the characters people you’d like to know, and the interrelationships between them perfectly complex.  Not to mention the series is darned entertaining.  Start with the first one, though.  Highly recommended