All you ever wanted to know about mouse babies

Question
QUESTION: "Mice go into estrus (heat) within 5 days after meeting a male.  They might mate the first day (maybe they even got interested during those first sniffs)" This is a quote of yours and I was a bit confused about what it meant.  I know that mice go into heat but I was confused when you said "within 5 days after they meet a male."  Does this mean that they only go into heat when they are living with a male?  Also is it posiblle to tell when a mouse is in heat?

ANSWER: Dear Jenn,

Yes, mice only go into heat when they have been exposed to a male.  Lucky things. None of that frustration that cats and rabbits deal with!  No, you can't tell when a mouse is in heat.  It would be a little difficult to take their temperature to determine their ovulation : )).  Let them do their thing.  Mice know very well what to do!  

squeaks n giggles,

Natasha




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

QUESTION: Oh dear.  Um I looked in my mouses' cage today and yesterday I forgot to put her in her own cage, so today I um noticed a small fresh scab on her ear so this could mean 2 things. 1) They have mated or 2) They go in a fight.

For some strange reason I think it's the first one, I hope not, so I'm just checking to make sure I'm wrong. ;-)

Also strangely I think I'm right and I even guessed when she would go into heat... strange...

Any way if they did mate please give me a run down on every thing from pregnant mouse to 6 week old healthy mice.

Thanx Bunches,
~Jenn

Answer
Dear Jenn,

If the bite is on the ear it sounds like mating.  Sometimes they do mate immediately-- I don't know enough about mouse physiology to know how mouse heat works, but my experience has been mating sooner rather than later.  Count the days : ).

The following link will take you to a bunch of YouTube links of mice mating, giving birth, and babies growing up (this person's mouse pair mated later rather than sooner):

http://en.allexperts.com/q/Mice-3824/2008/8/mouse-reproduction-mating-babies.htm

It will takes three weeks (21 days) after mating for the babies to develop.  If you want to avoid new babies 3 weeks later, take the male out before the female gives birth.  

The babies, or 'pups,' are born hairless and about the size of a baked bean.  The average litter is between 8 and 12 babies, though I have had a litter of one, and one of 18. They are dark pink. She nurses them every half hour.  Do not disturb the nest for the first week (only if it is easy to do so without disruption, you may peek quickly just to see
the little things!  They are funny-looking pink wiggly blobs with big black eye spots).  You may hold her when she comes out to run in the wheel or if she makes it easy to pick her up, and then only for a few minutes.  She has a tough job to do.  If she gets
upset she may try to move them out of the nest; this is dangerous.  If it happens,
gently return the babies to the nest and return her to it as well.  Anytime babies fall/crawl out of the nest-- sometimes there will still be babies hanging onto her teats as she exits the nest!-- gently return them to the nest asap.  She would do it, but you might as well keep them as warm as possible.  

After a week, the babies will have fur.  With someone else helping, begin to
gently hold them (warm hands!) once or twice a day for perhaps 5 minutes.  You
may have a tough time getting them out because she may disapprove!  When she is
on the wheel, take it out with her in it (I hope it is a stand-alone; otherwise
you have to scoop her out of it) and let someone watch her while you take out
the handful of pups.  Let them get used to your smell (hold both your hands
closed and very gently breathe into them).  Make sure they don't jump and hold them
over the bed, not the floor.  

At two weeks they will begin to open their eyes and go nuts!  The whole world
suddenly becomes a terrifying place.  They will be afraid of you.  They still
need to be held at least once a day for five+ minutes to get tame. This phase is
often called the 'flea' stage, or I call it the 'popcorn' stage.  They weigh
almost nothing and have strong hind legs, so they can jump up to two feet in the
air!  To get them out, try opening the nest and scooping them out before they
have a chance to run.  If you need to catch them (don't chase them around the
cage if you can help it), you may grab the base of the tail (near the butt) and
then immediately place the mouse on the palm of the other hand, keeping a gentle
hold on the tail until the baby is calm enough not to jump.  As soon as I get
them out I wrap them in the bottom of my T-shirt (pulling it up towards my face)
until they are calmer.  Then I let them out carefully one by one into my
gently closed hand.  When they are calm in my hand I hold them for another minute or
two, then put them back.  

Be prepared at any stage for the babies or mom (if you upset her) to nip you.
Don't throw them up in the air!  Most likely it will not break the skin and not
really hurt, just surprise you.  If the skin is ever broken (a real bite),
wash it thoroughly with hydrogen peroxide or antibiotic and watch carefully for
signs of infection.  You might want to let your doctor know but it will probably
be fine.  If a mouse bites you it means she is terrified, hurt, startled, or
defending her nest.  Try not to repeat the mistake, but if a mouse bites several
times, you may need to change your relationship with her.

At 3 to 3 1/2 weeks they will eat real food (mouse seed) and a week later will
begin to become sexually mature.  At 4 1/2 weeks separate the girls from the
boys (girls stay with mom) so you don't have any more unexpected pregnancies.
The boys may begin to fight after a while, so have a contingency plan for them!
Your pet store or vet may be able to suggest a way to give some away to happy
homes so you do not end up with too many mice. Do keep at least two girl babies
for mom to have as friends.  It's a pity to keep a single mouse because they
need each other.  

I have written a lot about taking care of pregnant mice and raising babies.  Do a little research in my archives so I don't have to repeat it all!  Other questions are always welcome.  Have fun!

squeaks n giggles,

Natasha