1. The bloodwork had something called a "BMI count," which on a healthy cat, has like 1 or maybe 2. His was 10. His kidneys have shut down.
2. There are a lot of toxins in his system on top of this, and he'll be unable to eat without being fed through a tube or introveniesly (excuse my spelling; I have no spellchecker at the moment). They don't know for sure if his digestive system has failed, but they have a pretty good guess it has, based on experience.
3. He has a serious heart murmur, but that's the least of his problems.
4. There are some other things, too, like a possible tumor in his sinuses, a bacteria infection on top of that, and so on. The vet listed them all, but I have forgotten most.
I was strongly encouraged not to prolong treatment because she said even if they flushed out his kidneys and hooked up food to his veins, the damage is already done, and he'd have another week at most. And because Artoo has severe digestive issues anyway, why do this to him? If it was a person who could still walk around and talk, yes, but try explaining to a cat, "Oh, you have to stay at the vet's, and be given meds, and be in pain and miserable, because we don't want you to die." Mother nature has always known best, and this isn't a curable thing. It would be as cruel as dangling him off a cliff, lingering his death.
He deserves better. He was the best cat ever.