The Dog Who Lost His Bark by Eoin Colfer

Patrick has been desperate for a dog of his own for as long as he can remember, and this summer, with his father away, he longs for a canine friend more than ever. Meanwhile, in his short doggy life, Oz has suffered at the hands of bad people. Somewhere out there, he believes, is an awesome boy — his boy. And maybe, when they find each other, Oz will learn to bark again.