Mac was down to skin and bones when he was tested for hyperthyroid. I can guess that that is not Fister's problem judging by his test results, but the vet (I love my vet!) gave Mac some appetite stimulating pills and they really worked! Within 24 hours, Mac was eating and drinking everything in sight! He had actually stopped eating at all, so it was a relief to see him gobble up all of his food! Is Fister on any appetite pills? If he is, maybe the Vitamin B would work to get him eating and drinking and putting on some weight. It can be difficult to keep weight on older cats.