Luckily it didn't come to that. He seems to be getting back to his old
self. He found a ball of wool today and played ping pong with it around
our bedroom ;) Problem is, Sox has always been more "picky" about his
food than Shoes-cat, so it takes a bit of careful watching to see if he
is just being a fussy cat or if he is coming down with something. Shoes,
on the other hand, will eat almost anything, anytime, all day every day!
He is so funny; we timed him yesterday: It only took 19 seconds for him
to appear when DH started sharpening our meat knife.... Shoes knows what
that means - "FOOOOOOD" and always gets any off-cuts when we trim
chicken or beef or whatever for supper. Sox on the other hand, will take
a tiny bit - occasionally.

Thanks for your concern!