Cost and how soon to let go.

[Rage812]

I have a Post about my Shih Tzu in here but had to compose myself before I write this question. My little Paisleys liver failed. vet has her on meds and she is up eating walking and going potty again but still sleeping a lot. She went from having fun to crashing in a few days to doing none of eating or walking etc. My question. Is this normal progression? give your pet this drug just to keep them going a little longer, The vet said there's nothing that can be done her liver it gone. She's a beautiful 10 yr. old Shih Tzu who wants to be happy and make you happy and it's hard to tell if she's getting sick. I don't want her to suffer and I want her to be with me forever, When will I know it's time? Does the vet end her pain there in his office. I wish he could give us both a shot so I don't have to endure this pain. Need to know what to watch for thank you