Nervous Mouse or Mites??

Question
We have two female mice, Cheddar and Swiss, sharing a cage since September 2009. Cheddar is typically a laid-back gourmet hanging out in the food cup and Swiss is the jock, running the wheel all the time. They have had their occaisional fights but have always slept together happily every night. For the past week or so their wheel has been removed from their cage. Everything seemed OK until yesterday when I woke up, checked in with the girls and saw Swiss had been given the barbering of a lifetime. She is missing a band of hair from around the front of her left ear, has considerable hair loss along her flanks, no hair on her left forearm or perineal area and is missing patches from her tummy.  Swiss is not continually scratching or biting at any of these areas or showing any signs of skin redness, crusting, or bleeding. she is eating well and reacts well to handling and plays well with Cheddar.  All areas of hair loss are areas she might easily reach with her teeth when self-grooming (except the band on her head).  Could she have mites or has Swiss (or BOTH Swiss and Cheddar) simply become bored and nervous without the wheel and  taken up plucking?  As this is only the 36th hour for Swiss's "new look" I heve decided to take a behavioral view of this and try to see if making her environment more interesting will help.I am presently cleaning the cage and re-stocking it with a new wheel, new toys and goodies for them to occupy their little minds. Any thoughts would be most appreciated.

Answer
Hi Maria,

The good news is that it doesn't sound like mites, and as long as there's no bleeding or scabbing from the barbering, it's not actually a big problem (it just looks really odd).  :)  It's certainly possible that Swiss is plucking herself, but it's most likely that the culprit is Cheddar.  It could be simple dominance, or it could be over-grooming between them.  Either one could spark up thanks to the unexpected change in the cage and Swiss being around more (now that she's not on the wheel all the time).  Adding more entertainment in the cage could help, but it could also just need to settle out.  As long as it stays cosmetic, you can give them a few days with no change to see if things even out again and their personal social order is re-stabilized.

In the meantime I'd provide a little extra soft bedding to keep Swiss warm, now that she's missing a bit of coat.  :)

Hope it works out in the near future!  :)
-Tam