Girl's best friend by Leslie Margolis
A Maggie Brooklyn Mystery. Bloomsbury, 2010.
Recommended for primary aged students. Maggie has a secret life. Unknown to her parents, Maggie is a dog walker after school. Not only does she have to keep this a secret from her family but a mystery needs to be solved. Dogs are disappearing and Maggie thinks she may be on the trail of a dog napper. She becomes involved with her ex best friend's missing dog and discovers that her secret crush, Milo seems to be part of the problem.
This book has a lot of appeal for primary aged girls - a good mystery, animals, issues with friends and boy trouble.
Lots of clues are revealed along the way and many of the characters are potential suspects in the dognapping saga.
The other book available in this series is Vanishing Acts.
Leslie Margolis has a great website with book trailers.