Pregnant mouse changes?

Question
QUESTION: I neeeeeed advice so bad.
My female mouse, two days ago, blew up like it swallowed a golf ball,
then she went back to looking normal, today she blew up again, it
looked like babies were moving around between her breathe, and I go
to look in there, pick her up and she looks normal? What the hell s going
on? Today is day 22 since I paired the male and female together. Is this
pregnancy or some kinda weird disease where she bulges up and then
down, she's panting and lays down quite often
She's a previous mother from a pet store, and has yellow fur around her
butt I guess from age.
Please help
Thanks

ANSWER: Hi Nick,

It sounds like she is having trouble giving birth.  Do you know if she could have had any of the litter yet and either hidden or eaten them?  That could explain the fluctuation in her size.  The panting and laying down often definitely makes me think birthing complications, for which there isn't very much you can do.  Make sure she eats and drinks normally so her body can do its best to complete the birthing process.  Also, since mice usually give birth at night, it would be a good idea to keep the light cycle regular and not turn it on more when checking on her if you are worried.  Natasha recently mentioned castor oil as a way of helping out a momma mouse, so if you can get her to eat just a bit, perhaps by dabbing a small amount on a treat, it may help.

I don't think, given the pairing 22 days ago, that a disease would be the cause of her bulgy tummy and panting.  This is good, though, because if she can successfully birth the children it means she'll be alright.  The staining around her rear is either due to a lack of energy or inability to properly groom herself, or may be due to fluids from trying to give birth.  You say she's getting old?  Risks of complications during pregnancy increase after a year old, so if she makes it through this pregnancy alright I wouldn't risk breeding her again.  Between 3 and 8 months is the ideal time, but of course, problems can occur no matter how hard we try to reduce the risks.

I wish her the best of luck!
-Tam

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

QUESTION: that's the thing, if she did give birth and ate the babies, wouldn't there
be blood somewhere on her bedding? And I was home all day checking
on her I feel like she may have megacolon which apparently makes mice
look pregnant and make her body bigger on either side or both

Answer
Although it is possible for mice to have megacolon, it is unlikely that a mouse purchased from the pet store would be at risk.  It is genetically tied, and so not something she could have picked up - it would have to be bred for.  To my knowledge, the problem is much more common in rats than in mice, and occurs more frequently in young rodents than in older ones (since it is genetic).

Since you paired her three weeks ago, and that is the gestation period for mice, it is by far the most likely that she is having difficulty birthing her pups.  I'm not saying megacolon or other intestinal disorders are impossible, since I'm not a professional vet and I can't see her in person; but from the clues we have and the timing it seems pregnancy is very probable.  How is she doing?  Did you try castor oil?  Is the environment stable and a normal temperature?  Is she eating and drinking?  Has she been breathing abnormally or having trouble moving around?  Make sure that you give her the normal night time period of darkness she usually receives so her body knows it's the right time to have those babies.  The quicker she has them, the better off she'll be.

It's not necessarily true that you would have to see bloody bedding as a result of her starting to birth the litter and cannibalizing them.  Some moms bleed more than others, just depending on how smoothly the pregnancy goes.  The mom normally consumes the umbilical cord and licks the blood off of them and herself before leaving them in a nest (ideally).  Therefore, it's possible it was just contained.  However, this was just a theory to figure out the fluctuation in her size - the more time that elapses the less sure we can be, and I don't have a way from here to tell you with any kind of certainty.

If you want to definitively rule out megacolon, you can take her whole cage into a vet that treats pocket pets and ask them for assistance.  If you do so, make sure you have an appointment set up first and arrive right on time so you stress her out as LITTLE as possible.  Tell them the problem over the phone while you are setting up the appointment so they can advise you about whether or not it is safe to transport her.  Since they'll be able to see her in person and in her natural environment, they will be able to figure out what's going on and how to address it.  Either cause should resolve itself one way or another pretty quickly, so make sure you do anything you can to make sure she is comfortable, well-fed, hydrated, and de-stressed.

Best of luck!
-Tam