In a bio lab, one is trained to pick up the mouse by his tail, lie him down on some surface where he can grip something with his hands, and then put 2 fingers behind back of his neck, and pull base of tail sharply to dislocate the neck. This kills him instantly.
One can then throw him away. The main problem with mice is not the mouse (they are so cute) it is the fact that they go to the bathroom on everything very frequently.
It is interesting that the animal protocols allow three ways to kill them which are considered painless.
1) Cervical dislocation from back of neck.
2) CO2 gas.
3) Decapitation with a big scissors from front of neck.
The latter is very much like shechita, so it seems science is now coming round to the fact that shechita is very humane, after all.