As some one who works at a vet hospital antifreeze poisioning intentional or unintentional is a horrible way for anything to die. Poisoning is NEVER a clean death and it causes unnecessary suffering for animal. Poisoning is a really underhanded and cowardly way to do deal with a problem dog or cat. If you are afraid for your family and animals then you should say something. Do you honestly think that if that dog is quietly taken care of that it will solve the problem long term? NO. People that are irresponsible dog owners tend to continue to be and their next dog will most likely be out running the neighborhood soon.