You’re losing sight of the fact that Ishmael is a work of fiction (and not a factual medical study) and I’m a novelist (not a physician or veterinarian). It was my task to produce some visible symptoms that would make it apparent to the reader and to the narrator that Ishmael was ill, but not so ill that the narrator would be prompted to call for emergency help. After the fact, however, it should be accepted as plausible by the reader and the narrator that these symptoms had been more serious than they seemed, so that his death would be accepted as plausible. In real life he might have died in the interval between the narrator’s visits without displaying any symptoms at all, but this would have been totally unacceptable to the reader. What I had to solve was not a medical problem but a narrative problem. The exact cause of death is completely irrelevant. What do the symptoms look like to you? What do you think they were supposed to look like? If Ishmael were a human who died after displaying these symptoms, what would you guess? Very relevant light is shed on the “narrative problem” in the sequel, My Ishmael.