There are probably more people who do this then is realized. I've been told in confidence by people who do this, and no I'm not going to 'prove it' because I don't go around betraying confidences. It's not something I would personally do, but I also don't believe that I have a right to make demands on how other people handle their animals. As long as it's a 'humane' euthanasia, whatever their reasons for doing so, are THEIR reasons.