You are here:

Mice/Fat mouse with labored breathing


I have a 6 month old black and white fancy mouse who weighs 72 grams (which is kind of fat and she was 79 grams about two weeks ago).  She has been okay and having a lot of energy until about a week ago when she started panting heavily and her poops got a little thin.  She has two bulges on her sides (thought this could be tumors but they are very soft to palpate).  About 4 days ago I began changing her diet to see if possibly she was getting allergic to some new treats I had bought for her.  The panting seemed to come down a little, but still present.  She has no coughing, wheezing, sneezing, nasal or eye discharge.   I thought she may be constipated so I began massaging her belly gently and she lets me do this with no problem and she seems to be pooping fine now.  I have read Mice are prone to tumors and cancer but she is so young.  I change her aspen bedding and water every 4 days like clockwork.  I wash her wheel at the same time and remove and replace all chew toys.  I am baffled as to what she may have wrong.  Any suggestions would be very much appreciated.

Dear Fred,

There are two main reasons for a mouse to pant. One is that it can't breathe and has pneumonia. I guess you could call it walking pneumonia, where there are no other symptoms but suddenly the mouse gets terribly sick and dies. A vet needs to listen to her lungs and if she is sick, get her on strong antibiotics.

The other reason is that she is too fat. Obese mice can overheat and pant. This can also be caused by too much protein in her diet.

If you are giving her anything else to eat besides her seed mix or mouse blocks/pellets, immediately change to just those. And bring her to the vet. Her life may be in danger.

Actually, you are right that a lung tumor could be the problem. Again, the vet may be able to tell.

I hope she is OK.




All Answers

Answers by Expert:

Ask Experts




I can answer questions about raising mice and caring for them as pets, with knowledge from my 38 years of having fancy mice as pets. I have NO MEDICAL TRAINING and you should take a sick mouse to the vet; but if you simply can't, I will try to help you. I LOVE PHOTOS!!! I ALSO LOVE UPDATES! Let me know how the little tyke is doing later on, for better or worse, especially orphans. It also helps me to help the next person. Please first search first: use 'Natasha Mice Mouse' with whatever else your question includes. Or check out these links: **** YOUR FIRST MOUSE (my video; rough draft): **** TEN VIDEOS ON RAISING ORPHANS: **** SEXING MICE: **** And some GREAT MOUSE INFO SITES:


I have had mice for 40 years (since I was 5!). I raised them when I was a child but now I keep all females, and never fewer than three so that if one dies the others are not devastated, because they have each other.

I run Rats and Mice are Awesome on Facebook. The official name is Rats are Awesome.

B.A., M.A., M.A. in Linguistics: Yale University and University of Connecticut

©2017 All rights reserved.

[an error occurred while processing this directive]