What's the Name of That Book??? discussion

Book about teenage boy turned into a dog by a curse because he made fun of voodoo practioner. Boy becomes a german shepherd I think and winds up being a seeing eye dog for an artist that has become blind. Boy gets seperated from artist, poisoned, and turns back into a boy right before being "put to sleep" in the pound. Boy finds artist a few months later. Artist has had a corrective surgery and has painted a picture of the dog he lost.

Yay! I think that is it! WOOHOO! I love that book