Henry visited the vet yet again today. Nothing was obviously wrong with him. No fever, no constipation, no obstructions. His most recent bloodwork in October. showed no signs of diabetes, kidney disease or hyperthyroidism. Given his history of mystery illnesses, the vet suggested doing some additional tests in a couple of weeks, i.e., when he's recovered from what's currently ailing him. The first would be a blood test to look for a certain type of bacterium. The second would be a biopsy of his gut. The doc wonders if he might have IBD or colitis. The doctor admitted, though, that it was a bit of guesswork on his part as Henry is a conundrum. He gets really sick for no apparent reason and then promptly returns to his old self. Assuming he doesn't get cancer or kidney disease, I otherwise see no reason why he can't live a long life, but that life might include some bumps along the way. He just seems to a be a sensitive cat.