introducing a new female to a pregnant female

Question
Hey, i was wondering if our two females will get alone. we introducewd them to each other when the eldest was pregnant and they fought a lot. and she has now had the babies and was wondering if it would be ok to introduce them to each other?

Answer
Dear Cassandra,

There is no harm in trying.  Most females will pair well together, but sometimes they just have irreconcilable differences.  And the pregnancy may very well have been the reason for aggressive behavior on the part of the expecting mother, who wanted to make sure there were no threats to her babies.

Handle them together and let them spend some time together in a neutral place like a shoebox.  If there is a problem here, there is a problem.  

If one mouse is the aggressor, introduce it into a cage where the less aggressive mouse has been living, if possible which needs cleaning!  The mouse smell should be strong so she will feel a little intimidated.  If you don't notice an aggressor, put them together in a clean cage.

Chasing and squeaking are very normal, and the squeaking is not from pain, but from mouse language (like a dog barking).  I only separate pairs if there is bleeding.  The chasing and squeaking may continue occasionally as they live together, or they may establish an understood order of dominance (similar to dogs, they need to decide who is the 'A-mouse').

If you do have mice living alone, it is important to have the cages as close to one another as possible.  The mice do communicate constantly, and a single mouse gets very lonely.  Also, if you have a single mouse it needs you to hold it a lot-- at least an hour a day-- though you might well be able to do this holding the two of them at once. Another thing I can do with more docile mice to handle them is let them sit on my shoulder, neck, or in my sleeve as I do other things such as reading.

I wish you luck!  It'll probably be easy.

squeaks n giggles,

Natasha