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Mice/My mouse keeps picking on the new mouse...



I recently bought a new mouse for my two girls (This one is a girl aswell.) and the oldest mouse, Pichu, keeps attacking the little one (Peanut). I understand that Pichu is only being the dominating female because it was her territory first, but when i got my second mouse, she was never this aggressive.
I was just wondering what some ideas would be to help stop Pichu picking on Peanut.

Thank you =]

Hi Sophie,

For the first few days, a little chasing and bossing is normal, but if you notice any violence it becomes much more serious.  How is she attacking her?  Do you see any biting, or does Peanut have any scabs beneath her fur if you blow backwards on it?  Do either of them show any strongly defensive behaviors like tail rattling (vibrating it against something in the cage so it "buzzes") or boxing (standing up on the back legs and punching out at the other)?  These are all signs that not only are they not getting along, but they should be separated to prevent real injuries.

If Pichu is just chasing her a lot, taking her food, etc., there are certainly things we can try to calm them down a bit.  First, make sure that there are ample supplies in the cage - never let them run out of food or water, and when giving them treats, be sure to give them each their own.  Second, if Pichu is guarding certain areas, try and remove anything they could fight over, such as extra toys or hides.  Changing the bedding can also help, as the cage likely smells like Pichu only.  Another good thing to try is to put a tiny, itty bitty dab of vanilla extract (real only - substitute does NOT work) under each mouse's chin and just over their tails.  This makes them both smell the same, and may give them enough of a break to settle things out.  If nothing seems to help, please write me back and we'll explore some other options.

Of course, until they establish who is the boss, scuffling may continue, but as I mentioned it should only last a few days.  Again, if you spot any violence, please separate them immediately.  It's not worth anyone getting hurt.

Best of luck, and congratulations on your new mouse!  Let me know if there's 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!

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