My 9.5 year old Smoke was just diagnosed with Hyperthyroid. I started him on the Methiazole 2x daily hidden in his food. He developed food avoidance after 2 weeks. He would eat around the pill and leave it behind even when I used nutri-cal or tuna fish and then he stopped heating all together. The lack of food caused stomach acid to build up and for a 24 hour period he vomited almost nonstop EVERYTHING that I was able to entice into his stomach. My vet gave him cerenia for 4 days to settle down the unhappy digestive tract. Then we started the methimazole at a lower dose. First 1x a day then graduated back up to 2x a day. I am worried about the long term impact the methimazole will eventually have on his liver and/or kidneys and digestive tract. I was looking into the I131 treatment. It involves radiation and an overnight stay of 3-5 days. Has anyone done this? How has the cats behavior and health been? Side effects? HELP!! I was told the prognosis for a cat on methimazole is 5 years max and I am not happy with this.