Awww, Christmas babies! I only ask because when we adopted our old American Eskimo there were a ton of papers. Her birth date and all that, plus all the things she didn't deal well with. She seemed fine with all those things oddly.
None of the remaining pets have any papers. Both cats came from farms, actually Kato did too. Well, Whiskey had papers I guess but my husband never arranged to pick them up -.- But as far as birthdays go we were told when both the dogs were born, and the cats are estimations.