It is very common incident which occur during the animal activity. Nobody cares for the death of any animal. I, myself, has been never cared the death of that mice. But i can say that it has induced a feeling of "Sanyas" in me. Why it happens to me, I don't know. But I can say that, watching any animal, while it was dying because of you, induced a feeling of "Virakti" in me.
That mice was not feeling well at the start of activity. its whole body was yellowish in contrast to the other mices whose body is slightly pinkish. When I have given the normal dosing to that mice, it had shown the writhings (a type of symptoms). But after some time, that animal started to strech its arms and legs and taking its last breath. After some time it began to throw its arms and legs very fast and repeatedly as the soul or spirit of that mice was leaving its body. I was watching closely to that animal. At last the mice had died. The spirit of that mice had leave its body to take birth in another body. The golden principle of "Gita" applies to everywhere.
On this, if I thinks that "I am the slayer", or the spirit of mice think that it has been slayed, then both of them don't know that I (God) create, destroy and then recreate to re-destroy. This is the endless chain of life and everybody have to face it.
This is the fact.