Since the cat has no way to protect himself I think you need to do it! I don't think you should allow the pup to bite the cat at all, and only allow her to play with him if she's gentle. We have 3 cats--they all have their claws, and each one was a stray before moving in with us. We also have 3 dogs, the youngest and smallest is the Yorkie. From the beginning nobody has ever been allowed to hurt anybody else, and for the most part they all get along pretty well. I would never allow one of the cats to hurt a dog, so surely I would never allow a dog to hurt a cat.
__________________  Shannon & Puff 
"All his life he tried to be a good person. Many times, however, he failed; for after all he was only human. He wasn't a dog." Charles M. Schultz |