Your arguments are absolutely preposterous. How would killing one's animals equate to killing people? People are far above animals. Killing the innocent in retaliation cannot possibly ever be justified on any level. As I said before, the only thing reasonably close would be if this was in retaliation for a similar act. Even then, the most appropriate response (in this context) would be a direct, and illegal, attack upon her.
Now, I agree that in this or a hypothetical situation someone could do something so heinous to another person that a response like this would not be surprising but it does not justify the response.
To clarify things let me say this. Should John Doe kill my wife, daughter, son, dog, etc I believe the appropriately illegal response would be to kill John Doe, generally not his wife, daughter, son, dog. Of course the legally appropriate response would be to let the legal system adjudicate him.
"I would rather claim to be an uneducated man than be mal-educated and claim to be otherwise." - Wookie 03:16