Thank you Heather for starting this discussion. I haven't been able to read everyones replies, but I will work my way through them as I can.
I currently have a cat going through a lot of what Grandpa is doing. OK, not barking , but vocalizing for no apparent reason, sometimes not seeming to be aware of me, sometimes confused, sometimes fine. Physically he checks out ok, so I just have to wait and see. (he's 15)
I just had a conversation with a friend at work whose cat is old and starting to have health issues. She's never had to make "the decision" before, and wanted to talk to me about how you do it (the emotional part). We talked a bit, and I told her I'd be glad to talk to her again when the time came. Unfortunately, I have plenty of experience.
And last, I am still struggling quite a bit with Sugar's death. I know she could have lasted a few more days, maybe even a week, so in that sense, I followed the "better a day to soon" rule. I still believe I did the right thing. She had problems getting around, and absolutely hated being helped. I promised her I would never put her through that again, and I kept that promise, but I still killed my dog, and sometimes it feels like it is killing me.
I know most of us have all been through this, and will go through it again. It is the downside of loving someone who has such a shorter life span. Is it worth the pain? Of course (for me, anyway). But it still hurts, it sucks, there's no way to avoid that.
I hope everyone who has animals they are "watching" has many more good quality days, weeks, months ahead, and when the time comes to let them go, know you are not alone.