introducing new mice

Question
QUESTION: Hi Natasha

I currently have 2 female mice, one about 15 weeks old who I have had for a
couple of months, one about 6 weeks old who I got last week with the aim of
getting a friend for my mouse, pumpkin (new one doesn't have a definite
name yet).

I've kept them separately for about the last week, letting the new one get
used to me and her new home. I've switched some bedding between the two
cages so they are slightly more used to each others smells and handled
pumpkin (the older one) after having the new one out so she gets used to her
smell on me, who she is comfortable being around.

The new mouse is quite jumpy is comparison to pumpkin who is very used to
me and very tame and friendly.

I introduced them to each other for the first time yesterday in a big cardboard
box so they had space and it was neutral. Pumpkin seemed to ignore the new
mouse who followed her round very closely sniffing her. I then had them both
on me and she seemed a bit more interested smelling the new ones face and
bum a bit so i put them in the smaller cage (where the new mouse lives at
the moment) and they were ok together in that they weren't fighting, there
was no squeaking and they just seemed to take it in turns to stay still and
crouched down and be sniffed by the other.
Because I had to work last night I put them back in their separate cages
because I couldn't keep an eye on them.

Today I've tried to introduce them again but Pumpkin seems very stressed
about it, running away when she can and staying very still when she can't. the
new one seems much more curious and seems to want to find her. Pumpkin
was also generally a bit more timid when I had her out beforehand not taking
the chance to explore places when she normally would.

When I put them back in their cages, the new mouse is very active, looking
and clambering up to the top of the cage whereas pumpkin stayed very still
when she first went back into her cage and then ran straight into one of her
shelters and hasn't come out (about half an hour ago) she is normally quite
active at this time of day.

I'm not sure where to go from here, I don't want to put them together if
Pumpkin is going to be scared all the time especially as it looks like the new
one might end up bigger han her given that they are already the same size.
On the other hand, everywhere says it is bad for them to be kept on their
own. Any advice you have would be greatly appreciated

thanks (sorry for the lengthiness!)

Jo

ANSWER: Dear Jo,

It sounds like you are being very careful with your two mice.  All of your ideas have been good.

I think Pumpkin will be able to handle the new mouse.  If you feel she has a disadvantage you can put the new mouse in her cage; otherwise make a fresh cage for the two of them.

Don't be surprised if there is some squeaking from the cage for a day or two.  Once they have gotten brave enough to really interact, they will either chase each other or one will be more dominant and do all the chasing.  The chased mouse may squeak loudly when there is absolutely no physical contact between them- the chaser is simply sniffing her behind.  You only have to worry if someone starts to actually bite the other-- and draws blood.  The squeaking is communication and not pain.  This might be a nice time to give them just a little treat:  Maybe a couple of pieces of buttered popcorn or even buttered bread.

I am surprised that your 6-week-old is the same size as your 15-week-old.  Are you sure it isn't a rat?  That's a joke ; ))

Give them 2-3 days to sort it out and if Pumpkin still seems unhappy, there might be something wrong.  Does she seem healthy otherwise?  Does her fur look groomed?  Is her back straight, or is she hunching over?  

I think they will be fine and once they have gotten to know each other a bit, Pumpkin will be very happy to have a new friend.  It was a good idea to get her one.

squeaks n giggles,

Natasha

---------- FOLLOW-UP ----------

QUESTION: Hi Natasha,

thanks for getting back to me quickly, everything you said makes sense. Just
one thing about pumpkin, she does seem healthy in that her fur is very shiny
and smooth and she eats and drinks and is active and curious but her back is
quite hunched when she's sitting up, is that a bad thing? I think it's always
been like that, when she's walking her body is quite straight but there's a
definite hunch when she sits back on her haunches. Is there anything I need
to do about it?

Thanks

Jo

Answer
Dear Jo,

If she has always looked like thaat, she is perfectly fine.  Mice do not hold their spines straight much of the time.  Some mice go straight in the wheel; others not even then.  No problem.  

Did you put them together?

squeaks n giggles,

Natasha