Update

Cat Couch here:

Well, about a week ago we came home to discover that Chatham had come downstairs. He hasn't come down the stairs in many weeks! He's done it about five times now, which is encouraging. He's still not getting his business entirely in the litter box (somehow we can't quite convince him that just because his feet are in the box that it means that his rearend is in!).

Starting last night he's not been feeling well - I think he's constipated, despite getting pumpkin and Laxaire. I'm taking him to the vet this afternoon to have him checked out (and to get "it" out if need be).

(In this photo, you can see how Chatham's fur on one side of his face is fading in color. Siamese cats are born light-colored and get darker with age.)