Sorry, not an expert, but I would definitely want to see the teeth. To separate yourself from the werewolf books, I think you'd need to stay away from the dogs with the wolf like appearance. That probably sounds obvious. I might just add a few images of what kind of dog you were looking for. I'm assuming you were looking for something other than the poodle. If it is the poodle, I saw a few excellent vicious poodle images that would probably work.

My daughter is an artist, and wouldn't be able to to the actual artwork, but might be able to help with general guidelines, in terms of what questions to ask.