Changing tails?

[Spiffy'n'Spunky]

I have three girls (Sadie, Sparkle, Silver) they are about 2 or 3 years old and I have noticed that thier tails are changing from pinky to like brown. Sadie had always had brown spots (she is dalmation color) on her tail but they seem to be getting larger and the others are changing too. I see them get into little scuffles over thier treats from time to time, but nothing serious. They appear to be perfectly healthy in all other aspects too. Anybody else know what this is?

[2pigs4rats]

All my rats get this as they gae, I have no idea what it is but it seems to me like dry skin or something similar, it doesn't bother them or anything.