We kept him going, for awhile. Then when we answered the question, "are you doing this for him, or are you doing this for you" we knew it was his time.
We found a vet who would come to our home to perform the euthanasia, which was a comfort, because I would have hated dragging him into the vet.
He was resting comfortably, on his bed, and we knew we did the right thing.
Good luck
You all need to look into Degenerative Myelopathy (DM). Shepherds have the problem too. It’s not all about HD - hip dysplasia. The dragging is often a giveaway to DM. My last GS (full of problems) definitely had HD though we never got her scanned or anything, and near the very end (the good thing was that she did not seem this way until 11), the vet said likely had achieved DM also.
I learned about DM first from a lady I “met” on-line regarding GS, “marjorie”, who created a website called Heaven’s Gate, dedicated to her dog Jack Flash and intended to document dogs and bloodlines with DM.