It's always a tough call. These little buggers become such a part of a person's daily life and it just tears at you when it comes to an end of life decision for them. My wife and I have always felt that once it becomes a dignity issue for that animal and it is going to hurt that member of our family to an extent that is more than should be asked of the animal to go through, then we will let he or she go, knowing that it will hurt us much more than it will hurt them. I totally feel your pain Walt! Little buggers anyways, they just enrich our lives so much, it is just too bad that they don't live on the same age clock as us.
Po is a beautiful cat BTW!! Awesome eyes!!