Another thing I read somewhere, cannot remember exactly where right now, but it was the results of a study done in Russia. The idea was to try to determine the effect on the mother cat of an injury or the death of her kittens.

 The gist of the study was that the kittens were separated from their mothers and taken out on submarines to ensure total sensory isolation from their mother.

Then the kittens were killed at sea while the mother’s vital signs-- pulse respiration, blood pressure, etc. -- were monitored at home. 

The mothers demonstrated signs of distress when the kittens were killed even though there was no obvious way that the mothers could know of the kittens’ death.

This made sense to me. 

     Somehow, a mother is connected to a part of her offspring or them to her. The kittens’ pain and death is experienced by the mother cat as personal distress and  perhaps, vice-versa. Of course, I do not understand all this scientifically but somehow it does make sense