If you know some with a dog you can borrow just take that in and say its a dragon and who can say different after all your in a made up country with a made up creature so we guess you can do as you like as they did in Narnia
I know I'm a little late to the conversation, but if you YouTube Art Attack, surely there'll be some ideas on there? Whatever happened to Neil Buchanan, anyway?
Buy a blow up dragon from a souvenir shop. Splatter it in plaster of Paris and once it's gone off you'll then have a perfect dragon plaster cast shape to work from.....