Since rabbits don't have paw pads, I think I'd base the paw print off of what rabbit tracks look like in the snow. While the good-luck charm of a rabbits foot still exists, in anthros it's more seen as a trait symbolizing good luck if you are born with them. At first, dean would probably think it is a bit ironic that this mark is more foreboding for him lol. Later on he would probably start to consider it more of a lucky mark given his relationship with cas.