I would actually be wary of using a mouse that showed signs of blunt trauma. I have heard that bone splinters, broken ribs etc can be dangerous for the animal consuming them. None of the (admittedly relatively few) mice that I have fed to my snake have shown any signs of trauma either. I am guessing that this is because it is far less hassle to gas them en masse than it is to bop each of them on the head with a small silver hammer. Any feeder animal breeders out there care to comment please?