Hyperthyroidism, methimazole gel and now vomiting in 13 year old female

My kitty, Mischa, who is now at least 13 years old, had been diagnosed with hyperthyroidism about 2 months ago. She couldn't tolerate the methimazole pill; constant vomiting and diarrhea. So now my vet has prescribed the methimazole gel and for about 6 weeks she was doing well. Last night she started vomiting again and also this morning. Then 10 minutes after I applied the gel this morning she vomited again (just mucousy stuff). Had not eaten anything before. Just wondering what I could be doing wrong. I am contemplating doing the radioactive iodine treatment ($1500). I had a cat previously who took the methimazole without problems until methimazole no longer worked. Then I had her get the radioactive iodine treatment which worked well. Does anyone have any helpful thoughts?

IMHO methimazole is a stop-gap treatment while you get the thyroid back to normal and make sure that doesn't play havoc with the blood pressure and thus every other organ in the body.  If you can do that and prove she can tolerate normal thyroid levels again, then get the radioactive iodine treatment.  I don't know anyone who has not been happy with that.

Hi, Her second blood panel came back with the thyroid level (s) normal and kidneys good. At first I thought that the cost of the radioactive iodine was prohibitive but now I am thinking I should go for it. The cat that I had previously many years ago tolerated the radioactive iodine well but she died 2 years later of heart failure during treatment for esophageal cancer at 14 years of age. I always sort of wondered if the cancer was related to the radioactive iodine but never inquired. It was a pretty rough experience for me. (This was 20 years ago but I still remember all of it like it was yesterday). Thank you for the info.

Think of it this way, she had 2 more GOOD years and then it was her time to go.  I have had a cat with esophageal cancer who never had radioactive iodine treatment, and I know several people who have cats who had the radioactive iodine treatment and are still fine today.  When dealing with an older cat, sometimes their time is limited anyhow, and perhaps her heart failure was a blessing because she didn't have to endure any more pain and/or treatments.  Since we can't change the past, it is best to find a positive way to look at it and then hang on to that.  The sad thing is that we usually outlive them, but it is even sadder if we don't.  Be sure to appoint a cat guardian who would be responsible for her if anything should happen to you.  They don't have to keep her forever, but just make sure she doesn't end up in Animal Control, or worse.

My late hyperthyroid cat did fine for over 3 years on methimazole. But in her last months and looking back over it all I always wished I had done the radioiodine treatment instead. It's possible some of the spikes in thyroid level and such over the medication time contributed to her heart disease she was diagnosed with late in life.

Basically I'm just throwing my opinion out here that if the rest of Mischa's prognosis is good, and it seems to be, I wouldn't hesitate to go for the radioiodine treatment. How many more years she will have you can never really know beforehand, but it could be several.

Hi again everyone. Thank you for your helpful comments. I think maybe I overreacted when Mischa started vomiting so much in about a 12 hour period after not having vomited for about 6 weeks. Since yesterday a.m. she hasn't vomited and she has eaten her special food (Royal Canin Urinary SO for feline urinary syndrome) and wet food. I am pretty sure we will be doing the radioactive iodine as I do not see how I could ask a cat sitter to do the gel while we are gone on an extended vacation. (Mischa might show herself or probably not, and then she would have to allow herself to be held; not likely.) And boarding at a Vet's hospital due to having to be medicated would be expensive. So anyway for now she seems to be back to her usual self. Thanks all so much for your help.

Tell your vet to check your cat's liver enzymes ( ALT, ALP, T. bili, AST)