Mouse wound

Question
Hi - My daughter has had two pet mice (supposedly females) for the last three months or so.  She came to me weeping a a couple of days ago holding one of the mice, which had a large wound around her hind quarter.  I separated the mice, cleaned the injured one's wound, and have been watching her carefully.  Other than moving slowly, she continued to eat and drink and her eyes are bright.  I was cleaning her cage tonight and before I put her back in cleaned her wound - the fur/skin fell off so she is "bald" all around her tail! It looks pretty disgusting as you can imagine.

Do I need to take her in to the vet?  Do you have any idea what could have caused this?  I've noticed some fighting between the mice prior to this incident.  

Thanks in advance for any help/advice you can share.

Answer
I am sorry this happened, please assure your daughter its not her fault.

The wound may be an abscess that has burst though you would have noticed a lump prior to the wound. It would be difficult for another mouse to create a large wound. Usually they leave bite marks or sometimes scratches and small rips in the skin.

It was the right thing to separate them and clean the wound. I would take her to the vet to look at her and sex 'her'. The store may have sold you males which would explain the fighting and severe injuries.

The important thing is that shes eating, drinking and its coming out the other end. It is a good sign she is behaving normally, however there is still cause for concern.

I hope she recovers soon, I would really appreciate you letting me know how she gets on. Please feel free to ask any more questions.