I got the cat off to the vet's office on Friday, and they immediately determined he was suffering from a severe urinary tract infection, which turned out to be the root cause of the nausea and lack of appetite. Simple enough to treat with antibiotics, but given the lack of food and water over the last few days, they suggested I leave him there through the weekend for further treatment, rehydration, observation, and recovery. That sounded like a wise thing to do so I agreed. As part of the overall treatment they did urine and blood tests, and they found some numbers in the blood test indicating Charlie is in the early stages of kidney failure. And though the vet didn't come straight out and say that when we were visiting the patient today (I took the kids up to visit the "cat hospital"), the discussion he and I had sounded very much like the beginnings of a management plan for a terminal illness.
Needless to say it's been trying the last few days. I didn't realize how strongly Charlie had integrated himself into our family until he disappeared downstairs earlier this week (his method of dealing with being sick is to go hide somewhere quiet until it passes), then was hauled off to the vet's by yours truly for an unexpected weekend stay. Katie and I went to visit by ourselves on Friday — and after our visit, she kept telling me she now understood the sentiment of not realizing what you had until it was taken away from you. Charlie wasn't quite the chipper cat on Friday, but he was today when I took this picture — both kids were loving on him and petting him (and yeah, me too), and I think it's the closest my children have ever willing stood next to each other.
In the meantime, I've been researching kidney failure in cats. It is a progressive illness, but it is manageable, and cats have successfully lived with renal failure for years. And it's actually a fairly common illness too, so there are lots of resources out there to help cat owners deal with it and manage the disease. The Feline Chronic Renal Failure Information Center is an excellent place to start learning. I suspect I'll be hitting that site quite a bit over the next few months.
A lot of this depends on how Monday goes. Charlie will get a second set of tests then to determine how much he's recovered with the treatment he got. This, in turn, will be a good indicator for what needs to happen next. Based on what I saw today, it looks like he's recovering pretty well, so hopefully it won't be too bad. I'm keeping my fingers crossed.