When I was young we had a great collie. The best. Eventually he got old and sickly. The hardest decision about owning a pet is when to have them take the journey.
Two trains of thought on euthanasia. One: the good days are over, now the pain and suffering have moved in with bags in hand. Letting the animal drift away peacefully may be the last act of love and kindness you can bestowe on your friend. No pain, just a sleepy trip to the sweet bye and bye. All things considered, not a bad way to go. When I was a boy I had another dog get smeared all over the highway. That was not a good way to go.
Two: The "don't pull my plug, I'll die when my body gives up on it's own" mentality. Usually held in regard by people who are either doing just fine or actually are attached to machinery that keeps the juices flowing and the will to live at all costs (surprising how tenacious that will can be when the chips are down) keeps them from stepping out.
Once I used to bartend and this older guy who was a regular just up and sold or gave away all his stuff and moved to florida. Didn't say why other than he needed a change of pace. Well about two months later we all heard that he had arrived in florida only to park his car on the highway and call the police to report that someone had committed suidide in thier car. He then reportedly hung up his cell phone and ate the barrell of a 38.
Now that's pretty horrible, but considering he had found out he had an inoperable brain tumor, I almost have to give him credit for knowing when the game was up and having the insight to take care of it before it took care of him. Kind of giving the finger to fate.
Don't know if any of this drivel helps your dilema, in the end you're the one who'll have to give the word.
If my story has any meaning I guess it's that sometimes we have to do what's tough to put an end to suffering.
Did'nt George Carlin once say that when we buy a pet we are in fact purchasing a future tragedy?