They still don't know what's wrong with him. He's definitely anaemic, but what's causing it is a mystery. They've ruled out quite a lot of stuff, though. They can't entirely rule out cancer, because they'd basically have to dismantle him to find out for sure, but it seems less likely now. Also FIV seems to have been pretty much discounted. His doctor seems to think there's some kind of immune-system thing going on. It could be a parasite he's had all his life suddenly triggering an autoimmune response, or a virus, or something else. Interestingly, the thyroid test our vet did showed him at the low end of the normal range, but the test they did at the hospital showed him at the high end, so he might suddenly have decided to take off into hyperthyroidism just to confuse everyone. They don't know.
Meanwhile, he's back, shaved in strange patches where they've taken blood samples and put a catheter in to sedate him and taken the bone marrow sample. He seems a bit more clingy now than he was, although according to the hospital he was a model patient. They were however concerned by his habit of sitting for long periods staring with his eyes mostly-shut into space, his head held at weird angles, and his habit of raising a paw in a Nazi salute when he wants something, which they'd never seen before. Other than being a bit more clingy, he seems fine. The doctor gave us some antibiotics to give him, in case it's a parasite or something that responds to antibiotics. If it is, we've got a head start on it. If it isn't, the antibiotics won't hurt him and we can discontinue them.
So we're waiting for the test results. Bogna went to the vet's on an unconnected matter this evening and he showed her a letter the hospital had sent him which thanked him for sending them such a `challenging case.' On the one hand, this is slightly alarming. On the other, the Queen Mother Hospital is a teaching hospital, and cases like this get a lot of attention because of what they can teach the students, so a lot of people are interested in what's wrong with him and how to make him well again, and that's good. We'll see.