Woke up to my (sick for a while at that point but still goin at a good clip) husky bloated, in pain and nearly immobile one morning. Her kidneys had failed and she couldnt stand to be touched when I went to take her in to put her down. I called around for a while and found a vet I still thank to this day (10 years later) who was willing to put his license on the line on a day off, meet me on the side of the highway and give me morphine to put her down at home so I wouldnt have to transport her. It felt right to do it myself and I was glad to not have to add to her pain by carrying her and driving.
OP I look at it like, can you do things to easily make your dog's failings better? Can you put down throw rugs so the floors dont cause an issue/pain? or does it require a major surgery on a old dog? If the dog has to go through a ton to continue, then were doing it for us, not them, and it's time.