pet mouse

Question
I bought two female mice from a local pet store a few days ago. I have kept mice in my 5th grade classroom for years, their average lifespan 2-3 years. Today, I noticed blood on the bedding, and observed what appeared to be her "insides" outside of her rectum. Since getting her, there seemed to be an unusual amount of waste in the cage. I have always kept two, and in just 3 days, the cage was covered in poop. It also seemed that the food disappeared really quickly. Every time i saw her, she was eating. There was even food In the house. I have never seen that behavior in mice. Could she have "eaten herself to death"? Seems silly, but the diet I was feeding her was very different than the pet store. Also, I noticed by day 2 that her eyes were only half-opened. She looked sick. Just want to make sure it wasn't something I contributed to. I do not use pine bedding, as I know this can cause issues... The other mouse appears to be fine.
Thanks!

Answer
Hi Michelle,

What you're describing sounds like a prolapsed rectum.  If she has an intestinal problem, she may be eating more to compensate for having difficulty absorbing nutrients from the food.  This could be a result of an illness or a hereditary problem, but it needs to be addressed immediately if she is still with you (you mentioned eating herself to death, so I'm not sure, I'm sorry).  A vet that specializes in pocket pets can help you identify what caused the problem, and if it is an illness, help her if still possible.

Just in case the problem was caused by an illness, it's important to clean and sanitize the cage immediately.  Gastrointestinal illnesses are almost universally acquired by the fecal to oral route, meaning if the other mouse tries to eat food contaminated with the sudden large amounts of poop, she may be at risk of contracting something.  Since we don't know what caused the prolapse, it would be better to be on the safe side and completely clean the cage and replace the bedding and food.  If the sick mouse is still with us, you may want to separate them as well until the problem is resolved.

Either way - this is absolutely nothing that you caused!  A change in diet can at worst cause a little diarrhea, definitely not death or even a sick appearance.  I would just keep a close eye on the eating and waste habits of the healthy mouse to look for early warning signs, and if 2-3 weeks pass with no problems, consider yourself out of the woods!

Best of luck, and let me know if I can help with anything else.
-Tam