Hi Tressie, Rat tail is caused usualy by over production of oil from the ferret's oil glands anf the pores get clogged. It's usually a seasonal condition which is seen during the warmer weather months. In the past 16yrs I have seen this more in males than females. You can treat it by washing the tail and keeping it clean. I supose to much oil added to the diet can cause this too but rat tail is not seen in every ferret whch makes me believe it is caused by individual chemical makeup. I used to shave my ferret's tails and clean the tails but now I pretty much leave the tails aloce because as cooler weather shows up, the rat tail dissapears. Debi [Posted in FML 7473]