Peter Pettigrew's animagus transformation after Goblet of Fire

Question

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.

Answer 1

His animagus will not have a mettalic paw

Looking at Rowling's writing on Animagi,

An Animagus has a great potential advantage in the spheres of espionage and crime. For this reason, an Animagus Registry exists on which all Animagi are expected to log their personal details and the precise appearance of their transformed self. It is usually the case that distinctive markings or disabilities belonging to the human body will transfer to the animal self. Failure to enter oneself onto the Registry may result in a stretch in Azkaban. When the process of becoming an Animagus goes wrong, it often goes seriously wrong. Impatience with the long and complicated process is generally at the root of such disasters, which usually take the form of horrible half-human, half-animal mutations. There is no known cure for such mistakes and those who make them are often forced to live out their days in their pitiable condition, being unable to become fully animal or fully human.
_{Pottermore - Animagi (behind paywall)}

The new metallic hand isn't a "distinctive markings or disability belonging to the human body". It's a creation of Voldemort's which Peter clearly doesn't have control over.

Without pausing to think, Harry tried to drag back the hand, but there was no stopping it. The silver tool that Voldemort had given his most cowardly servant had turned upon its disarmed and useless owner; Pettigrew was reaping his reward for his hesitation, his moment of pity; he was being strangled before their eyes.
_{Harry Potter and the Deathly Hallows - Chapter 23 (text available for free on Pottermore)}

As such, it is probably safe to assume that it would not be carried over to his Animagus form.

In addition to this, we have a canon precedent for one's Animagus form not changing after first appearing.

The animal into which one turns, if an Animagus, seems always to be that which becomes the Patronus. There is no known instance of the Animagus form changing to match the Patronus if the latter changes, but the Animagus who can also produce a Patronus is highly unusual and no study has ever been done on sufficient numbers to draw firm conclusions.
_{Pottermore - Animagi (behind paywall)}

Though this is referring to a much a bigger type of change, and Peter's Animagus did change when he cut off his finger.

Answer 2

So, on Pottermore, in the "Everything you didn’t know about Animagi" section, it says:

Your Animagus may embody a distinguishing feature of your human self An Animagus may seem the perfect disguise, but once you descend into your animal-self, there may be a distinguishing feature about you that stays. For example, Rita Skeeter’s beetle has little glasses-markings around the eyes, and in the famous case of Wormtail, both he and ‘Scabbers’ were missing a finger.

Notice the "may", not "will". There are two ways to look at it: either the animagus will have an identifying feature that could be anything, physical traits being reflected would be just one of them. Or the "may" refers to things other than the body for people who don't have a noticeable physical feature, like Rita's and Minerva's glasses marks, but all marks on your body will show.

I couldn't find other canon references of physical characteristics affecting the animagus form. That's all the solid and relevant information I could get you, the rest is guess and speculation, and it all comes down to how you interpret the may.

Peter's missing finger wasn't on the lost hand, so he would have two distinguishing features? And he should've had a distinguishing feature before losing his finger, which means it changed or added up. Meaning he would probably also have a silver paw added up besides the missing finger.

Unless the distinguishing feature is not mandatory as the may suggests, and Peter already has his, so further changes wouldn't necessarily happen. And his silver hand may acts as a real limb, so it could not affect the transformation. And from everything that we learnt about how transfiguration works from the books, I think it's very possible to transform something perfectly, and the distinguishing feature is just a perk from animagi in specific.

So to my understanding, it all indicates that it's very likely that his animagus will suffer no distinction, although I can't say I'm sure about this.