A paw print on a girl's chest could mean several things, depending on the girl's choice of paw, and the personal significance the paw might have for her. Tattoos in general mean different things to different people.
The breast tattoo is a very sexual placement for a tattoo, as it may be asking for attention to that particular place. The paw print itself, whether it be a dog, cat, deer, wolf, tiger or other animal, could also indicate a specific, unique meaning as well. The print could have personal significance, or it could just be an act of rebellion or portrayal of style.