It's been over a month since his last post, so I'm happy to report the news is still good; Ollie is making a steady recovery. He took a 45 minute walk recently with no ill effects, and his hydrotherapy is down to twice a month. Plus his fur is grown back somewhat so he looks a whole lot better (which bothered us a lot more than it bothered him, frankly).
I took this photo a few hours ago, and we just finished playing (carefully) with his beloved tennis ball; he really is himself again. It's safe to say we are all much more confident in his back successfully weathering a summer on Aspö.