Thanks, guys, for all your prayers and good wishes. I'm more sorry than I can tell you to have to say that Gus is dead. His kidneys shut down entirely, and there was no choice but to euthanize him. Doug and our younger daughter (who lives in town) came down to the hospital, and we spent a good (if tearful) hour with him, petting him and telling him how much he meant to us--what a good dog. Then the kind doctor gave him a shot, and we brought him home and buried him out back, under a big eucalyptus tree, beside old Ajax, our doberman who died a couple of years ago. We buried him with a MilkBone between his paws (his favorite), and a small bouquet of fragrant herbs from my garden--rosemary (for remembrance), lavender, and sage. He always loved to help dig in the garden.
We're very sad, but relieved that he's out of his trouble. It's been a bad few days.