Hamilton is already starting to do better, as you can see from his healthy appetite. He eats on top of the refrigerator so we can keep his food away from our other cats, who would happily down it all before Hamilton has a chance.
Karin, in her comments below, is right. Surgery is one of the options for hyperthyroid treatment, but apparently now there is something else (besides a lifetime of medication) -- a single injection of radioiodine. The procedure can cure most cats completely, but it does require being hospitalized for 1-2 weeks and it's as expensive as surgery. We're hoping Hamilton will be a candidate once they determine if he is otherwise healthy (no kidney disease). Fingers crossed! It won't be the first time, or the first time this year, that we've pulled out the credit card for veterinary bills!
I'll keep trying to get a discussion going -- has anyone else had experience with this treatment?