We didn't end up taking Hobkin to Athens. Our vet got him stabilized in an oxygen box with periodic Albuterol treatments and gave him a Lasix injection to decrease the fluid in his lungs, but Hobkin refused to eat anything at the vet’s all day. However, when I got there, I managed to coax him to eat a decent-sized (and messy) meal from my hands; the trade-off between overnight veterinary care versus him stressing out and not eating with strangers wasn’t a good one. So he’s at home now in a makeshift oxygen tent.
I’m cautiously optimistic, but it’s still definitely touch and go. And it's going to be a long night.