I have seen nude mice before but not the rat version. I was short of feeders a few weeks ago & bought in about a hundred assorted rat & mouse pups from a local lady. These were from a litter of browny/black fuzzies which were very skinny & rough looking, so I put them under a female rat to build them up. I fed most of them off as they grew, before I realised they were shedding fur. I kept these few to see what happens. The nude mice I had usually grew fur again & looked normal, but these guys just keep getting balder. They are also more active & a bit wilder than albino stock rats. Has anyone seen bald adult rats before?