We have three ferrets with the tatoo on the ear from MF, and BELIEVE ME, they hear just fine. The other one we have, Sharkie who doesn't have a tatoo IS deaf. You can't assume a tatoo means medical problems. Tatooing could be just to let you know they are neutered and descented, they are from a certain breeder, but it doesn't always mean deaf. Like I said we have three with that tatoo and they all hear just fine, they are so perky and alert when they hear something. Bob [Posted in FML issue 3217]