Whew! I'm so glad to hear that he has something that can be treated. I hope that the pills will do the trick and that he'll return to his old self very soon. My RB Storm also had hyperthyroidism but he was put on Methimazole 2.5mg and he was on 2 pills a day. He'd get one in the morning and one in the evening. I would wrap them in part of a pill pocket and he just thought that he was getting a treat. Before he was diagnosed, I do remember that he was drinking a lot more water than usual and he seemed hungrier too. He had also lost some weight which I didn't even realize because of his long fur coat. He never needed an increase in his doseage like some cats do and he was also on pred which also increased his appetite because he also had small intestinal disease. I thought his medicine was kind of expensive but I did buy 200 pills each time so that I didn't have to keep going back to buy refills so often. I actually still have some of his pills left over. I hope Mac is easy to pill. Good luck.