Baldur got another X-ray and an ultrasound today. (We were hoping the traveling ultrasound docs would be available and they were. I had to drop him off for the X-ray in any case.) The pleural effusion is much reduced and they told me to cut the dose of the medicine he's taking for that. The ultrasound told them that his mitral valve is leaking; this is caused by old age but the hyperthyroidism isn't helping. So they said to boost the thyroid medicine to a rate that I understand to be somewhat astonishing (20mg/day of Methimazole, up from a high 15). I asked if I should spread that out (giving it to him three times a day instead of twice); they said no, increase each dose.
Last night and this morning he lapped up tuna juice but didn't eat any solids. They reported that he ate "a couple bites" of canned food while there today. When I got home I gave him some gravy-laden food and he showed actual interest for the first time this week, so I take that as a good sign.