Javascript is either disabled or not supported by this browser. Javascript is either disabled or not supported by this browser. This page may not appear properly. A Mice a very territorial.
Females tend to be a little better then the males, but the males are overall the worst.
The only exception to putting two male mice together, is if they are from the same litter of babies, or introduced to each other when they were babies. A This is a very common incodent that occurs. She could have been too young and didn't know what she was doing. The main reason is threat. There could have been a lot of reasons for why this happened.