This has been puzzling me for some time now (Read: It's 01.30 and I just thought about it).
We know that changes done to a person's body will to some degree transfer over to the Animagus form of wizards and witches. A good example of this is the marks around Mcgonagall's eyes (while in cat form), similar to her glasses. This was also how Sirius found out about Scabbers being Pettigrew (at the start of PoA), Sirius spotting that the rat was missing a toe on its front paw.
Now, Scabbers/Wormtail being such a small animal, spotting a missing finger/toe would be quite hard while the rat is running around in general. Sirius spotting this in the newspaper was lucky since Scabbers didn't move much in the photo. However, during the resurrection of Voldemort in GoF, Pettigrew cuts off his other hand, which is later returned in the form of a metallic prosthetic.
My question is, since we don't see much of Pettigrew until DH, will his rat animagus form also have a metallic paw in place of the one he cut of? I can accept that there will be speculations, since I myself couldn't find anything in the books explaining this, but I really want to hear opinions for or against this.