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Mice/Field mouse


Our apartment building in mid-city Los Angeles proper just had an influx of field mice. Our apartment, alone, had five, four of which were caught and killed by my miniature schnauzer mix. I managed to catch the last one in a bag of chocolate. We've been feeding her guinea pig pellets, fresh fruit and little bits of chocolate here and there. We gave her a little water bottle from petco and she seemed happy. But when we woke up this morning we found her dead, I know for a fact that she was still alive and jumping around two days ago. We've had her for about 2 months maybe three and I don't know why she passed. I know it's difficult to answer questions without being able to have seen the mouse in person, but maybe you could provide some general causes? I think Squeaky was around two months when we caught her. Thank you!

Hi Joanne,

I am so sorry for your loss.  You're right that there are a lot of possible causes.  Mice, like many other prey animals, tend not to show that something is the matter until it is very serious, so it's likely that she would not have shown any signs until briefly before her passing.

Nutrition is a possibility, but not a likely one, since typically nutritional problems show themselves early on.  Hamster mixes contain different vitamins and different levels of protein and fat than required of mouse diets, which could cause problems relating to metabolism or deficiencies over time.  Again, I think you would see evidence of this long before it actually became bad enough to hurt Squeaky.  Also, chocolate contains both theobromine and caffeine, which, while it affects mice much less than say dogs, can still be a bad idea in more than teeny tiny amounts.

Chemicals in the environment could also lead to toxicities over time, depending on if your complex uses any spray poisons for pests or plants.  There is also no telling how old Squeaky was for sure, she may have been quite a bit older than you guessed and just smaller because of the difference in lifestyle.  Genetics could also play a very big part in her passing - genetics can lead to a higher tendency toward internal tumors, developmental problems, organ failure, or any number of other nasty things that could lead to a sooner than expected passing.

Lastly, it could have simply been a fluke, such as choking on her meal.  Mice have accidents just like people do, and without a necropsy and histopathology report, it can be very hard to guess at what exactly the reason was for her passing.

Whatever the reason, my sympathy goes out to you.  Mice are great pets, and I hope losing her doesn't discourage you from keeping them in the future.

Best wishes,


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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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