Mouse has wounds on tail

Question
Hi! I have two white Female Mice, one has bites all the way down her tail. I'm a bit worried about this. It does not look like they are fighting? I cannot think of anything that would be stressing her out. The other mouse is fine. Any feedback on this would be greatly appreciated.

Answer
Dear K,

If you have never seen them chasing each other, and never heard any squeaking -- and are around the cage enough of the time that you would know-- then it is possible that, rather than mouse 2 biting mouse 1, mouse 1 is actually biting her own tail. This could either be a result of a psychological disorder, or be the result of self- barbering, which is when a mouse gets overly concentrated on washing herself.

Because you can't take a mouse to a therapist, the only thing you can do is to try to distract her. More toys in the cage, possibly including wheels of different sizes, and things to climb on, and treats hidden such that she has to work to find them (for instance in a tiny box with holes in it to start them off), can help. Adding another mouse can also be a distraction. It is best to have three in any case; then when one dies, there is not a mouse left who is not only devastated from the loss, but also a single, lonely mouse, both of which conditions may lead to depression, and render her more likely to get sick or get mites.

Best of luck to her!

Squeaks,

Natasha