Blue, my "old man" started with a thyroid problem in December of 2010. We started him on medication (methimazole) and he wasn't getting much better. We did more bloodwork this past December and upped the dose. (from 10mg per day to 30 mg per day). He was doing great, but still not gaining enough weight, so we upped the dose again (under the vet's guidance) to 40 mg per day. Everything was good, but Blue started slowing down and having trouble jumping up like he used to. I figured it was just age (he is 15) and ignored it because it was never very severe. Recenty he took to meowing LOUDLY at night and last time, that was a sign of the thyroid issue. I called my vet and took him in for a thyroid blood check on Thursday. Just now,the vet called and frantically told me to cut him down to ONE PILL (he was taking FOUR) a day because his thyroid was dangerously low. It was a 2 and was supposed to be 15-50. She said his heart could stop and the level was scary to her!!! She was obviously concerned and she scared me half to death. I asked her if I shoud just stop all together, but she said no. Does anyone have any experience with this??