"I cannot count how many times I have thought of that night, rehearsing my mistake, thinking of wiser things I should have done," said Professor Quirrell. "I later decided that I should have thrown my wand from my hand and changed into my Animagus form...

Though Harry was careful not to touch Quirrell's snake form in Azkaban, this quote implies to me that Animagus forms might be more resistant to the Riddles Doom effect. This might apply to Harry as well, should he ever be in his Animagus form.