Introducing a new mouse to the cage

Question
We have a single female who has been living alone for over 12 months (we have recently adopted her).  Can we give her a friend by introducing a new female to the cage?  What should we do to ease this process?  

Answer
Hi Fiona,

Yes, you can definitely introduce a new girl to the cage.  There may be some chasing for the first day or two, but it's nothing you'll need to worry about unless you see boxing (standing on the back legs and punching with the front) or biting, or see any kind of injury.

Making sure there are plenty of spaces to hide from each other in the cage will help, as well as making sure there is extra food available.  Cleaning the cage and the toys and changing the bedding before adding the second mouse should also help make the addition go a little smoother.  If you give treats while they are still getting used to each other, give two so they don't fight over it.  I have also heard of dabbing a small amount of real vanilla extract on the chins and rear ends of both mice so that they can't tell that one of the other smells different.  Other than that, just give them a little time and separate them if you see any real aggression.

Best of luck!
-Tam