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Mice/Is my rescue mouse pregnant?


Hi experts. I rescued a pair of mice 3 days ago, and I am concerned one of them may be pregnant. I have not been able to get close enough to her cage mate yet to look at its genitals as he/she is very shy! Of course it is possible that she is just on the chunky side.. they were kept in an ice cream tub with no toys or wheel!! I will be monitoring her weight now, as she absolutely loves running on the wheel, but just wanted your opinion! Have attached a pic. Thanks.

Hi Kat,

It's certainly possible that Peanuts is pregnant, though the only real way to be certain is to wait and see if babies show up!  In the meantime, it would be a good idea to house the two of them separately, just in case.  Mice become fertile again the same night they have their babies, so if the other mouse is a male, you would be risking a dangerous back-to-back second litter if they are still together.  If the other is a female, it MIGHT be fine, but sometimes stressed females will injure the babies, so separating as early as possible until you know more is ideal.

Mice take 21 days from getting pregnant to having their babies, or pups, give or take a couple of days.  That means all you have to do is wait three weeks and watch for babies!  Make sure she has plenty of water and food, and a safe and private hide to nest.  Try not to disturb the hide, because the babies might be quiet at first, and you don't want to disrupt them!

If babies don't happen, then you can put them back together after day 23 or 24.  If the other mouse is a male, however, they will need to remain separate (and you'll have to watch for babies 21 days since initially separating them), unless you are intentionally breeding them.  Since females go into "heat" every five days, there's no way to keep them together without tiny baby surprises.  :)

If pups do come along or you have any questions about them, please feel free to write me back and I'd be happy to help out!  Thank you for rescuing the little guys!  :)



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I can answer questions regarding mice as pets, mouse behavior, color and coat genetics, breeding techniques, and general health questions. I can help with caging and setup, nutrition, social issues, and what to do in most mouse emergencies (such as unplanned litters, injuries, fighting, etc.). I can also assist with questions pertaining to orphaned mouse pups, weaning litters, and questions of mating and birthing. I cannot answer questions about exotic or wild varieties of mice such as spiny or pygmy mice. *****FOR EMERGENCIES, anything requiring immediate medical intervention, PLEASE take your mouse to a professional veterinarian or wildlife rehabilitator who works with mice as soon as possible! IMPORTANT RESOURCES: Raising Orphaned Mice: Orphaned Mice Videos: Natasha's Your First Mouse: General Mouse Help: Mouse Info and Exotic Breeds:


I have enjoyed the companionship of mice nonstop since 2004, and spent a year caring for them in a lab where I learned a great deal about their breeding, social needs, and health. I spent a few years breeding them, specifically working with albinos, marked mice, angora mice, and satins. My education never stopped - I am learning something new every day from current and well-established research thanks to the wonderful folks at the Jackson Laboratory, as well as from my wonderful mousey friends online. I also love learning from my terrific questioners here on AllExperts - you folks keep my passion for these amazing animals alive and well!

East Coast Mouse Association - expired, American Fancy Rat and Mouse Association - expired

Partial University for a B.S. in Microbiology, Partial University for a 2-year degree in Veterinary Technology (RVT cert), C.E. classes in pathogens, aseptic technique, genetics, and applications

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