Mainly, there was a lot of fluid either in or around his lungs, which was odd because he didn't show any signs of having difficulty breathing. The bloodwork didn't show platelets to be low enough to justify that much fluid, either. The most plausible explanation has to do with the mass they found, which Dr. G told us she spent about twenty minutes with the other vet debating whether or not they thought it was cancer. The verdict: even if it is, there's not a whole lot they can do about it, since it's right in the center of his chest--radiation wouldn't hit it, and operating is obviously a bad idea.
So things don't look good, but, as Dr. G pointed out, Oreo's surprised us before. We got some extra painkillers and upped his Prednisolone dosage, and we're preparing for the worst while hoping for the best. Right now, we're feeling okay, but it's kind of a roller coaster. I don't know if it's harder to watch him try to walk or to watch him lying on the floor with his eyes open because he can't get comfortable enough to sleep (on the other hand, that's just an assumption, so maybe his eyes are open because he sees something wildly entertaining that we can't see?).
Today I'm thankful for finding Biscoff cookies at Winco (if only they'd had them when we were playing Portal; they might have helped with the motion sickness), Dr. G continuing to be a super awesome veterinarian, the small signs that maybe the extra painkillers are helping Oreo to be at least a little more comfortable, Mom being kind enough to take us to the store today, and having Psych to cheer us up.