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Mice/Sick Mouse



I noticed about 5 days ago that one of my mice seemed ill.

She's about 3 or 4 months old. She was sold to me as a feeder mouse from Petsmart. I have her housed in a large cage with several other mice. They all get along, none of the others are exhibiting symptoms.

The ill mouse has a scruffy, dingy coat. She has lost weight. She is lethargic. She is keeping to herself (when ordinarily she socializes with the other mice). She doesn't want to come out of her cage (which is also unusual). I cannot be sure, but there seems to be some discharge coming from underneath her tail.

She appears to be able to eat and picks at her food a little, so I think her teeth are alright. I can't tell if she's drinking water or not, though.

I'm not sure what is wrong with her. She used to be active and happy, and even kind of pudgy. Is there anything I can do to help her?

Thank you.

Hi Dani,

How long has it been since you got her?  Have any of the mice come home with you in the past three weeks?  If she or any of the others are this new, there is a possibility one of them could have brought home an illness from the store.  It can take up to three weeks for symptoms to show from anything that they could have been exposed to in the group tank at Petsmart.

Or have there been any other changes to their cage dynamic - new additions or removals that may have stirred things up?  Sometimes if they are trying to sort out who is boss in the cage, there could be some bullying going on.  This could result in her drinking and eating less because she feels less comfortable doing so, or is actively being prevented from getting to the water bottle by a more dominant mouse.

The symptoms you are describing, namely the poor coat, lethargy, and weight loss, are symptoms both of illness and dehydration.  You might consider pulling her from her group cage and observing her in a less busy environment.  She will still need affection and attention since she won't have her friends, but you will be able to keep a closer eye on her condition and habits.  This is a good idea whether it's a social problem or an illness, since she'll have her own food and water and hide, and if she is sick, there will be less time spent spreading the potential disease with the others.

This will also allow you to observe her pooping habits.  You mentioned discharge coming from beneath her tail.  There is a condition called wet tail, which is a highly contagious fecal-to-oral route bacterial disease that causes diarrhea, dehydration, weight loss, lethargy, low appetite/thirst, hunching, and poor grooming.  If you suspect this may be the culprit, time is of the essence, and she needs to see a vet who works with rodents/pocket pets immediately for rehydration and antibiotics.  By moving her to a cage of her own, you will easily be able to tell if she is passing normal stools or having watery, loose stools, and be able to rule this and other gastrointestinal diseases out.

In the meantime, while you determine if there is a vet that can help in your area or if it is possible, try offering moist treats like stale bread soaked in water or baby food (no added sugars, fruits and vegetable kinds like apple sauce or carrot are good choices).  As long as she is eating and getting hydration, she can recover.  If she stops either of these things, she needs to see a vet immediately.  Is there anyone in your area who can see her and help out?  I know a vet is not always possible, so if there is absolutely no way, please write me back and I will try to see if there is anything you can get to give her at home.  Hopefully, however, by isolating her for observation and giving her one on one attention, you'll be able to find out some more information about what might be causing her poor health.  Please let me know what you find out so I can give more targeted help and advice!  I want to help out however I can.

Best of luck, and let me know how she does!


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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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