I stopped by the vet's tonight to have Erik weighed. He has lost half a pound since early September. :-( I thought he was feeling bonier, but it's hard to tell when you pet him every day.
His appetite has been varying -- never absent, which would warrant some amount of force, but it's been lighter than it ought to be for the last couple weeks. Sometimes he won't eat cat food but will eat baby food or tuna; sometimes it's the reverse. Surprisingly, he currently seems to like a certain type of dry food, which he usually only picks at.
I have (finally!) noticed a possible correlation; both this cycle and last his appetite has done this at a certain point in his drug cycle. We're going to vary that next time and see if the behavior follows the drug.
The doctors who did Erik's ultrasound in June said I should do another if his weight drops. But the surgeon I saw in July said the ultrasound was hard to read because the surgery he had a few years ago rearranged some bits. Tonight my vet asked if I'd consider another ultrasound and I asked her to explore whether it would actually tell us anything we could act on. What outcome could an ultrasound serve up that we could treat without surgery? (If all roads lead to surgery anyway, what does the ultrasound tell us?)
In July the surgeon postulated four possible causes of Erik's woes: the hepatitis we're already treating, a pancreatic tumor that would be untreatable, IBD that would be treated with prednizone, and lymphoma that would be treated with prednizone and chemo. Of those, only the tumor could be visible on an ultrasound; exploratory surgery could diagnose all of them (via biopsy), but surgery is risky. Prednizone interferes with biopsies; his recommendation was to either do exploratory surgery or decide not to and just treat with prednizone speculatively. I delayed on making a decision on surgery (and thus not doing the prednizone) because surgery is scary and Erik seemed to be doing ok; now I find myself leaning toward "just hit him with the prednizone". The surgery poses non-trivial risk; I don't see enough benefit to put him through that. But my vet will talk with some folks and explore these questions. And I forgot to ping her about diet changes (she didn't have any ideas there this summer), so I'll do that. (She did give me a tube of NutriCal tonight as a possible way of getting more calories into him.)