Cannabalizm

Question
I have 2 females and 1 male in a cage i keep my mice in. There were (estimated) 14 pups in the corner of the cage. Anyways, so I was checking on them, when I saw that there were only 4 pups with the mouse who was nursing them. Then, I found a pups head with a body next to it. Then, later the fourth pup had some skin on its back removed so muscle was showing. I wanted to put it out if its misery so i flushed it down the toilet..
So the male and non-mother female were cannabalizing the pups. I separated the male and non-mother. Was the cannabalizing of the pups normal? and the mother doesn't seem to be paying much attention to the pups. Is this because it was the mothers first litter?

Answer
Hi,

Mice should never be kept in mixed sex groups, this only creates unnecessary stress for all parties. The mother always needs a comfortable habitat of her own after she's gotten pregnant, up to the day the young are separated (and even then she should NOT be placed in a habitat with a male immediately - she needs rest!)

As for the cannibalism, it's quite common for a first time mother, but giving birth in the same habitat with two other mice, one being a male, and the chances for it sky-rockets. The male may also kill and mutilate the young as an instinct. The Finnish Show and Pet Mouse Club's site has a very detailed guide to breeding mice: http://hiiret.fi/eng/breeding/index.html

Also, flushing a living baby mouse down the toilet isn't the best way to the handle the situation. The most humane way would be to cause a major blow to the back of the head, which causes nearly instant death if done properly, instead of slowly drowning. Hope this helps.