Introducing a Baby Mouse to the Big Girls

Question
Dear Natasha:

I had three mice, Shimmer, Georgiana, and Mask, all females.  Shimmer recently passed.  I would like to get a new mouse, in case Mask or Georgiana passes and the one remaining won't be lonely.  However, I am worried about introducing a baby mouse to the big girls.  Will a baby mouse be accepted by Georgiana and Mask?    

Thank you!

Answer
Hi,

You're doing exactly the right thing. Female mice should live in threes for exactly that reason.

A baby mouse is pretty easy to introduce because it isn't seen as a threat by the others. You'll want to completely clean the cage they will go in. Make sure nothing smells like the adult mice-- wash accessories in a very mild bleach situation and save anything wooden or paper for later. Make sure the bleach odor has a chance to evaporate before putting the mice in. Put the baby in the prepared cage along with whatever litter or carry box or whatever she has that smells like her, in the cage too. Dab some REAL vanilla extract on each mouse's neck and rump. This makes them smell the same. Only the actual, real vanilla extract, not vanilla "essence."

When you put them together, do it in the morning when they are sleepy.  Expect chasing and squeaking. Even though the baby is squeaking loudly, it is usually just communicating. It is a good sign if an adult mouse chases the baby and the baby rears up on its hind legs facing the adult mouse. This is the mouse exposing its jugular, in effect saying "my life is in your paws, don't kill me, I'm just a baby!"  Everything is OK unless:

--there is blood.
--the baby becomes depressed and sits there and doesn't like to move
--the baby doesn't have access to food, water, or the nest.

Most likely they will be sleeping together by the next day. Make sure there is only one obvious place to sleep so they are likely to do so.

It is better to introduce two babies at the same time, so each one gets harassed half as much; however you might be drawing the line at three mice.

Good luck to the new one(s)!

squeaks n giggles,

Natasha