Those drugs are magic, and he's ambulatory today. Toddling and woozy, but ambulatory. I'm grateful for all your kind comments. I'm off work this week, so I can keep an eye on him and cater to his every need. No walks for two weeks, the vet said. Riley will be in heaven--no more slow meanders in the morning, waiting for his geriatric brother; I can walk him as fast as he wants to go. Up trees! Into bushes! After squirrels!
(You should have seen us yesterday--the vet told me over the phone to give Boscoe a dose of Metacam, which we had left over from some previous emergency, but that Boscoe should get food with it. So I brought out a half-cup of kibble and fed it to him by hand before giving him the medication. Boscoe ate it happily, without even raising his head from the bed. This is the life! You could hear him think. Except for this stupid back pain...)
Photo of a confused Boscoe taken about twenty minutes ago, by Doug, the best dog photographer I know.