over-grooming

Question
Dear Expert,

We have three great little ratties: Sue and Gracie came home with us about a year ago, and little Phoebe just joined them in June.  Sue has a bad habit of grooming Gracie rather aggressively behinmd the ears, creating bald spots. Since we got Phoebe, she is doing it less to Gracie, but of course now she is doing it to Phoebe, too. Is there anything we can do to prevent this? I thought about putting something yucky on the fur, but when we tried Bitter Apple, she just licked that rigth off. Also, I don't want something yucky on the "victims" because it may prevent them from grooming themselves.  Suggestions?

Answer
 Unfortunately there isn't a lot that can be done about it.  It is usually a dominant behaviour and can result from her trying to prove her dominance over the other rats.  It can also be from a mental problem that causes her to do this.  The only suggestion I can make is to make sure they have lots to do in their cage, perhaps even making their cage larger if that is possible, and take them out for free play as often as you can.  Rats sometimes barber other rats (or themselves) out of boredom and keeping her occupied may lessen the behaviour.

 If she isn't causing them any actual harm (the skin looks fine, just the hair is gone) it is all right to let her do it, it won't hurt the other rats to have a bit of hair missing.  If there are wounds on the skin you may want to consider separating Sue from the other rats if she is causing too much harm, though in this case she may turn the  behaviour on herself if she is left alone.

 Well I hope everything turns out all right, I'm sorry I couldn't have been more help!  Barbering behaviour can be very hard to get rid of once the rat picks it up, if at all.  Good luck!