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Mice/Mouse breeding


Hey Tamarah,
I have been trying to breed one of my mice this is the second male she has been with and nothing has happened at all. She has been with the 2nd male for 17 days and no luck any idea what could be going on? Both times she has been with a male they haven't tried to mount her right away. I added a different female with this male and this is the 2nd day they are together he sniffed her genitals and then she sniffed his but he didn't try to mount her or anything any tips you could possibly give me.

Hi Dan,

Most of the mating is going to occur overnight (in the dark, when they are left alone), so it can be hard to determine if mating is or is not happening - especially since it only takes a few seconds.  They may indeed be mating and need a couple of cycles before being successful, or he might not be a suitable male.  The best way to determine if the problem is him or her is to give them a little time, which is important, because successful breedability may indeed be a heritable trait.

What I would suggest is removing the female now and waiting the full three weeks from separation to see if she is, in fact, pregnant and just not showing yet.  Her time frame for birth if mating was successful would be three weeks from the first day they were together until three weeks from when they were separated - so you may be due for pups anywhere from 3-21 days from today, give or take a day.  I would also suggest leaving the second female with him for a total of 14 days, removing her, and waiting the same time frame (another 7-21 days after separation).

I usually try 2-3 times with the same pair before giving up, but since you are using different males and females, what you learn from who is successful and who is not will help you pinpoint the weak breeder(s).  The ideal breeding mice are healthy, not obese, between 3 and 12 months of age (some say less), and neither so aggressive that they stress their partners nor so passive that no breeding gets done.  If the mice that carry the traits you are trying to pass on don't meet these standards or are not successful after 2-3 breeding attempts, it may be time to both evaluate the environment for causes (are there reptiles in the same room?  Is there stress on either males or females?  Are their living environments suitable, clean, and with enough resources?) and consider breeding new mice.  Some mice are not great breeders, and that is okay, but there is no reason to try to pass that down to the next generation and make your life (and theirs) that much tougher.

Best of luck, and let me know if there is anything else I can help with!


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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

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