I had a similar experience with one of my ferrets.  Her tail is squared off
instead of tapered and covered with a fur tip.  You can actually see the
skin at the end of it.  I got scared as the fur got shorter and thought she
might have some terrible disease so I rushed her to my vet.  After a careful
exam under bright lights he laughed and asked me which one of the ferrets
was a barber!  Turns out someone is clipping her tail short.  I haven't
caught the culprit yet and there is no chewing or biting just a nice neat
clip.  He suggested bitter apple but you wouldn't want to use that on
whiskers.
 
Laurel
[Posted in FML issue 2359]