I would like to add a little something else. the fact is that most of
the time those of us that adopt and love our cats (or other pets) are
eventually going to be faced making the decision on when it's time to
euthanize. It's tough and it's a fact that some people do wait too
long, so I think this is a good place to post this article. It is an
excellent overview of euthanasia and ends with a wonderful article
that I think will help the majority of people that read it. I would
advise people read it well before they are faced with having to make a
decision.

http://specialneedspets.org/euthanasia.htm