My mice ate their mom.

Question
I had a mouse who was black with a white stripe on it's back i bought her a year ago and she was still as healthy as ever. She had given birth to two litters in her life, and most where girls. I put the males and girls seperated. Today I had to go out for at least four ours the mice had water and food and they where fine. When I came back the mom was riped apart from her jaw to her abdominal area and a bit lower. It look so scary her insides where riped inside out and her jaw was lying there next to her body. It was cleaned of any meat. I live in california and recently it has been getting really cold so I left the heater on 60 degrees. on top of that I wanted to mention that my mice are a slightly bigger than regular mice and the mice that have the dominant black on their coats tend to be petite. Can any of this have caused this?

Answer
Dear Vanessa,

I'm so sorry about your tragedy.  What a terrible thing to find.

When a mouse is found eaten or half-eaten by another mouse, it almost always means the mouse died of something else.  Mice are programmed to eat a corpse because in the wild there is no human to remove it and it could rot and foul the nest, making the other mice sick.  Although four hours is a short time, mice can die of instant heart attacks just like people can.  If the mice were truly fine four hours before, then the cold couldn't have killed her.  However, 60 degrees is too cold for pet mice. The temperature should be between about 68 and 73 degrees. If there was no fighting before, the size of the mice has nothing to do with it.

My condolences.

squeaks,

Natasha