Methimazole Alternative for Hyperthyroidism

kjc1020

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My cat was diagnosed with hyperthyroidism in July. We immediately started her on Methimazole and her thryoid levels quickly regulated. However, after about a month of treatment she developed extremely high liver enzymes along with vomiting, refusal to eat, and noticeable pain. After stopping the methimazole, this fixed itself quite quickly.

The vet and I are stuck on what to do. She has CKD and an intense hatred of other cats, so is not considered a good candidate for iodine treatment. Given her adverse reaction to methimazole, the vet is hesitant to try that again. She's doing ok overall, mostly vomiting periodically, showing occasional nausea symptoms, and breathing a bit quickly.

Any ideas on alternative treatments or ways to manage this? She is 13 and has had largely non-progressive CKD for about 6 years, but is otherwise healthy. Thank you!
 

FeebysOwner

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I am curious about how high of a dosage of methimazole your cat was on. The potential for adverse effects is much greater when the dose that is given is too high. It seems a lot of vets prescribe a high dose with the idea in mind to bring down the thyroid level quickly. Quickly is not always better. It doesn't allow the body to gradually adjust to the meds. Normally, the dose is started out on the low side, testing is done after 3-4 weeks, and the dose is adjusted as needed, with another test follow up 4 weeks later, and possibly another dose adjustment. It can actually be a few months of this process to get the thyroid level in the normal range.

Some vets want to go as high as 5mg twice a day; others at 2.5 mg twice a day. After researching and discussing it with others who have hyperthyroidic cats, I convinced my vet to start with just 1.25mg twice a day.

You might ask the vet about the dosage - and also ask if the transdermal version might be worth trying. While toxicity can still happen with the transdermal version, less is actually absorbed into the body, reducing the chance of adverse effects.

If not that, a dietary change to the prescription foods for hyperthyroidism is the only other option I know of if the I-131 treatment is being ruled out. You might want to look a little further into the iodine treatment first. As far as I know, each cat is somewhat isolated for a few days after treatment, so the exposure to other cats might not be as great as you think. Of course, that will all depend on the facility you would be using. Here is a web site, albeit difficult to navigate, that explains a lot do with the treatment options, with a focus on the I-131.
Animal Endocrine Clinic | Where science and compassion cure
 
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kjc1020

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FeebysOwner FeebysOwner Thank you for the response! We had her on 2.5mg twice daily transdermally. I asked the vet about a very low dose if we try methimazole again. He said we might get to the point we need to try it eventually, but he thinks she is doing well enough he wants to take the watch and wait approach vs risk the liver issue again because she was so sick and in so much pain from less than a month of methimazole.

She cannot handle seeing, hearing, knowing another cat exists, etc. Its bad lol. So unless they keep her sedated I think she would be terribly agitated and worked up the whole time she's there.
 

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Any ideas on alternative treatments or ways to manage this?
Hi

My boy already has liver issues and is a low stage kidney kitty, and has just been diagnosed as hyper-T.

We aren't going to do the surgery so the only option for us is managing it through diet. It's working, the only issue at the present time is that the Hills y/d canned cat food is not on the shelves (the dry version is available), and I've just sent yet another email to Hills, yelling at them to not give me the party line about blah blah we're working on it and talk to your vet about finding anther food option, since there is no other option commercially.

You could consider raw/home cooked as long as you find a way to lower the iodine and keep the phosphorus down (in other words commercial premixes for raw may not be the answer, you'd need to check with the manufacturers to find out about phosphorus and iodine content).

Weruva and their Soulistic and B.F.F. canned and pouch cat foods, while not low enough in their iodine content are low, and they have several versions of low phosphorus foods, as well as the WX line which is extremely low in phos.

My point being that you might be able to manage her thyroid quite well with Hills y/d dry and a combination of (now and then) commercial canned plus raw. If Hills gets the canned y/d on the shelves fairly soon you might be able to just go that route. (Poppy's not eating it on his own but since he needs supplements that he's also not eating on his own, he's getting handfed, and his weight is stable :) ).
 
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Furballsmom

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She cannot handle seeing, hearing, knowing another cat exists, etc. Its bad lol. So unless they keep her sedated I think she would be terribly agitated and worked up the whole time she's there.
Oh, by the way, are you using calming products and Cat Music?
 
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kjc1020

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Furballsmom Furballsmom Thank you for the advice! I just requested approval from vet to buy Y/D so I'll give that a try. She likes the Weruva BFF food (though mostly the seafood ones) so perhaps the two together will at least let us manage this. Thanks again!
 

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(though mostly the seafood ones)
Right or wrong, --and I'm neither a vet or a nutritionist, but in this case as long as the iodine and the phosphorus numbers are as low as possible I'm not that focused on the fact of fish, since both Poppy and your kitty are consuming other foods which hopefully offsets any ill effect from the seafood. We just don't have a lot of room to maneuver, so I'm trying to pick my battles and thread the needle all at the same time, to use some handy phrases LOL

You can double-check the nutrition levels on Weruva's website, for B.F.F. and and then the specific ones she likes (the nutrition content isn't the same for every variety), so you can select the ones with the best lowest numbers.
 
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catmando2

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My cat was diagnosed with hyperthyroidism back in August. After evaluating the various treatment options, I knew for sure I wanted the I-131 treatment. I'm still a bit fuzzy as to what makes a cat a candidate or not? Is the recommendation by vets based mostly at looking at the lab results? Or do they assume the cost is too high (though in my mind, as long as the cat may be around a few years, it's I-131 is the more cost effective route).

A vet at first had me try the methimazole as transdermal gel. This was pretty much a fail as my cat doesn't like getting his ears touched. I say out of about 10 tries, got a good dosage about twice. Then I told the vet's office that I wanted to try the pills. The starting dosage was 2.5 mg twice a day. For about two weeks I could see a big improvement. But after the first follow up labs, the vet said his T4 levels are still too high. Dropped from 10.1 to 5.3. So he upped the dosage to 5 mg in morning and 2.5 mg at night.

After about a week, I noticed my cat showing side effects. Eyes very watery, starting to lose hair around the "eyebrow" area. I talked the vet to drop the dosage down to 3.75 mg in morning and 2.5 mg at night. Did this for a few days, then luckily, someone cancelled their I-131 appointment so now I have my cat off med, scheduled for I-131 in about 1.5 weeks.

I agree with others that vets probably should start on a lower dosage of methimazole then gradually increase if needed. No fun having a cat get rough side effects.
 

neely

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I'm still a bit fuzzy as to what makes a cat a candidate or not?
A cat diagnosed with H-T is considered a good candidate thorough a physical exam, T-4 test, two view thoracic x-rays, CBC, blood pressure and urine analysis. The OP's cat has CKD which may lessen the chance of being a good candidate.

K kjc1020 I agree with Furballsmom Furballsmom about the diet approach and hope this will help your cat. Best of luck and please keep us posted on her progress. :crossfingers:
 

neely

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I should have mentioned that although the I-131 treatment has a high success rate Hyperthyroidism can mask other health issues that are revealed post radioactive iodine treatment. Our cat had the I-131 last December which was successful and his T-4 level went down but at the 6 month check up he was showing signs of high blood pressure and is being treated for that now. It's not unusual for H-T to mask other health problems too, e.g. kidney, heart disease, etc.
 
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kjc1020

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Thanks all for your thoughts. We decided to give the methimazole one more shot on a 1.25mg dose 2x per day; I started her on that Thursday. Unfortunately the Y/D diet is not available right now, so pretty limited options. She seemed good for a few days but didn't want to eat this morning (hoping its a furball issue, not the liver again). Vet wants her in later this week to do a full blood panel to check liver as well as a VDI test to assess possible IBD/lymphoma in case that is causing the vomiting and nausea.
 

neely

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Best of luck with the reduced dosage of Methimazole, that's the dose our cat was on too before getting the I-131. 👍 I hope the full blood panel goes well, please keep us posted on the results.:crossfingers:
 

Furballsmom

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An update, the canned Y/D is back in stock at Chewy. You can't give the med along with the food, but managing the thyroid through diet alone might be a very viable option.
 
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kjc1020

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Thanks for the update! We tried her on the methimazole again but same thing happened with her liver so we stopped it. A few weeks ago, we also got a diagnosis of likely intestinal lymphoma. Vet started her on prednisolone and chlorambucil and it has made such a difference! She's eating well, hasn't vomited in nearly three weeks, and just generally seems to feel so much better.

Her thyroid values were elevated but not too much, so now we wonder if it was the intestine causing her symptoms all along. I'm cautiously optimistic she'll maintain at this level for now and we can just keep an eye on the thyroid.
 

neely

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We tried her on the methimazole again but same thing happened with her liver so we stopped it. A few weeks ago, we also got a diagnosis of likely intestinal lymphoma. Her thyroid values were elevated but not too much, so now we wonder if it was the intestine causing her symptoms all along.
I'm sorry to hear about the new diagnosis of intestinal lymphoma but glad her thyroid level is only slightly elevated and she's eating well. Fingers crossed you continue to see some improvement on the new meds. :crossfingers:
 
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