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Mice/Sick mouse


This Morning I noticed my mouse Tassie was very sick.
His stomach was extremely bloated and he was struggling to breathe. He was also making a strange noise while trying to breathe. He was fine yesterday
I called the vet and was due for an appointment this afternoon but sadly Tassie passed away.
I was wondering if you had any idea what was wrong with Tassie?
I am curious to know as I have other mice and want to keep them healthy and safe.

Hi Shauna,

I am so sorry to hear about your loss.  These things are never easy.

Unfortunately, the only way to be sure about what caused a death is a necropsy and pathology, which can be very expensive, and are not always done on animals as small as mice.  Necropsies also have to be done virtually immediately, before there has been any chance for decomposition.  The bloating could indicate a few things, such as something toxic, an internal problem such as an intestinal blockage, distension, or damage from an injury, or even a severe allergic reaction.  The first thing I would do when you feel ready would be to check around the cage or cages for any new chemicals, objects, or foods.  Is there anything in the cage he could have fallen a long distance from?  Do you spray the area with any kind of pest poisons or insect treatments?  Are there cleaning supplies near the cage?

If there are no obvious chemicals or new foods, treats, or other items that could have caused an accident, then I think the most likely cause is something internal such as a blockage or allergic reaction.  These are not always predictable and can be genetic, so I do not think there is any risk to your other mice, but I would check the area very carefully just in case.  If you have recently changed the sort of food you use or bedding, check the other mice for wheezing, swelling, or any other signs of an allergic reaction in case anyone else is sensitive to it.

Again, I am so sorry for the loss of Tassie.  If there is anything else I can do or help with please let me know.



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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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