Late on Monday his back legs gave out entirely. There was much whimpering and crying (on his part. There was some on mine too, but that is beside the point.) and we had to carry him into and out of the house. Not that it did much good, from a "I think he needs to go out" point of view, since a dog who can't stand ... But he wanted to go out. His appetite was unimpaired (not exactly a good thing, under the circumstances, but I thought it was a good sign that he wasn't in much pain), but he mostly couldn't even lift his head. He looked pretty bad. And in the very early hours on Tuesday morning he needed to go out, fell off his couch and moaned pitifully until we took him outside. He was actually able to stagger to the middle of the back yard, and we let him sleep out there. The next morning I went out to check on him and at first thought he was dead. He was lying there so peacefully. But he was still breathing. And in a couple hours he got up.
And he's been lurching around ever since. Still eating fine, too. He is reluctant to sit or lie down, so inside the house he paces (he did not want to pose for a picture, in case you can't tell!). The Energizer Doggie. Fifteen years and he's still ticking!