Haha thanks Ok so I checked over everyone, it seems contained to just 3 or 4 babies from that littler. Everyone else is fully furred, soft and healthy. Although from what I was reading, you'd need a microscope to see them :/ I'm thinking maybe it's over grooming, or possibly like with human children where they get bald spots from laying in one place too long. They little ones are always at the bottom of the pile. Would it hurt to treat them all for mites? I'm not a fan of over medicating...