17 yr old cat w/ hyperthyroid; treatment questions

My 17 year old cat was just diagnosed with hyperthyroid, last week, after taking her in for an exam due to weight loss and early morning dry/spit vomiting episodes. In addition to the thyroid thing, vet also mentioned that her liver enzymes were up, and suggested a couple of approaches.

Approach 1 - schedule liver ultrasound ($700) to understand what is happening there before putting her on meds.

Approach 2 - skip the liver diagnostics and put on meds, knowing it has side effects and may interfere w/ her appetite and possibly her liver.

Complication #1 is that my kitty has always been a pickier eater, though we’ve got her to the point that she’s eating wet food and my other cat’s hills z/d dry food, moistened.I think as a symptom of the thyroid issue she’s actually gotten better about eating, so not great.

Complication #2 is that my other cat (the exclusive hills z/d eater) is a freakshow when i bring the older cat back from the vet. Its days of stress on the both of them until they readjust. She’s got major ptsd from an extended hospital stay a few years back. i feel for her but she’s just awful when the other cat comes home smelling like the vet.

That said, we were on board with doing the liver ultrasound and are currently trying to get it scheduled (its a traveling service and basically waiting on them to schedule with our vet- guessing its going to take awhile like most veterinary things right now), but in the meantime I’ve been doing some reading (dang internet lol), and I guess there is some indication that hyperthyroid cats can have elevated liver enzyme issues and that is typically resolved by treating the thyroid. So now I am wondering if it even makes sense to jump to the ultrasound first - one because of the expense, but moreso because of the stress it puts on both cats.

At the same time, it sounds like there is some risk by giving the thyoid medication to a cat with liver problems.

I also read, and it wasn’t discussed with me, about the thyroid y/d food we could try. So now I am wondering if we try transitioning her to the y/d first, knowing Ms Picky may totally reject it and that we may be back to this medication vs liver situation.

I do have a call back in to my vet to discuss these options again and to have her answer these questions, but wanted to know if anyone here has had a similar issue with their hyperthyroid cat and the approach you took?

Does the liver ultrasound change your treatment plan? What are the expected findings there?

Methimazole is cheap and easy. Unless you/the vet thinks the result of that liver study will rule out methimazole & put you on an entirely different treatment path, AND you/the vet thinks that finding is likely, I’d treat with methimazole and retest on a fairly short timeline.

And, in my experience, inappetent cats are inappetent for a reason. Treating that makes life a hell of a lot less stressful–for everyone. I start with famotidine 2.5 mg 1-2x day. If that doesn’t do it, I put them on mirtazipine, which is an old antidepressant that makes a fabulous appetite stimulant–it makes them hungry AND happy.


Ya, I’d skip the liver ultrasound too. If she were younger, and there was some long term concern about something something, it’d be different. But she’s 17, so. The meds will pick her weight back up and she’ll feel better.

My cat wouldn’t eat his pill, so I would just pop it in his mouth every day. I wouldn’t worry about whether she’d eat it, it’s easy to give it yourself.

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Skip the ultrasound. The reason her liver enzymes are up are because she is not getting enough calories right now and the liver is trying to fail. Simkie’s approach with the famotidine is a good way to help and the mirtazapine really works if you get the gel to put on their ears. Every vet I have worked with (and I have had three cats with thyroid issues) has told me that they don’t care what the cats eats so long as it eats. Get kitty feeling better and then work from there.

And why do cats have to act like such jerks when their “sibling” or room-mates come home? Whenever I take Duncan in and bring him home, his brother Jack has to hiss and growl at him for a couple days and his sister, Pearl, runs away from him like he is poison. Poor Duncan - the only cat that wants to interact with him is Baler the “baby” and he hates Baler.

Hyperthyroidism can cause elevated liver enzymes. I suppose if her thyroid is only mildly elevated and her liver enzymes are significantly elevated then the two may not be related. I would probably start treatment for hyperthyroidism and then recheck blood work in a few weeks, and if her liver enzymes are improved, then it was due to hyperthyroidism. If they’re not improved, then proceed forward with more diagnostics such as an abdominal ultrasound.


I can also add that Methimazole is cheap and easy as I have a cat with hyperthyroidism and it costs me like $35 a month from Wedgewood Pharmacy. I do want to add that there are multiple ways to administer methimazole if your cat is like mine and hates taking pills or easily spits them up. There’s a dermal version that you can rub into their ears, but you have to keep an eye out for ear infections if your cat has sensitive skin like mine.


Has your vet mentioned radioactive iodine treatment for the hyperthyroidism? This is expensive up front, but it will cure the hyperthyroidism. Not all cats are good candidates for this, and 17-year-old cats often have other significant health problems. But if your cat is otherwise healthy, it might be something to consider.


I had a cat about that age ( as far as I could tell as he just showed up at my house one day) that was diagnosed as hyperthyroid. Methimazole bought him about 2 or 3 good years before his liver started to fail. I used the pills and started out wrapping them up in a small chunk of mozzarella cheese because he did not like pill pockets. After a while he refused the cheese so I used pork tenderloin. Up until the end he was pretty good with the pills with this regimen.

At his age I could not justify the radioactive iodine treatment. I don’t know how long the methimazole treatment is effective but the vet felt the time I got with this cat was pretty normal. However he may not have been up to date on this issue so that may not be true.

This is all really great info and is helping me formulate additional questions for when i speak to my vet later today (hopefully)- so thank you to the power of COTH! The vet that called me to talk about the bloodwork results is new to the practice and not one we’ve seen yet- and I don’t feel like I got a lot of information from her but also because I wasn’t really prepared to ask some questions. You get what you put in, I guess. But I am also questioning some of the things she told me- or maybe didnt go into detail about- whether its because she wasn’t knowledgable/rushed/I didn’t ask the right questions - I don’t know, but now I need clarification. After a few days of processing the news, reading up on additional info, I have more questions and going to speak to my actual vet to get some answers.

The radioactive iodine treatment wasn’t mentioned to me - I discovered it while reading. I am going to talk to the vet about whether or not my girl is a good candidate and go from there.

I am super familiar with cerenia, famotidine, mirtazipine - my other cat was on all of those a couple of years ago when she fell ill. I did actually ask the vet on the phone about usng some of these to counteract any possible side-effects of the thyroid drug, but she kept glossing over it. It was this weird thing where I wasn’t sure if she heard my question or processed my question differently in her mind. Im not sure, it was a strange call.

It does seem reasonable enough, provided the test result #'s for the thyroid and liver indicate- to jump to medicinal treatment and look at the liver values when we do the retest, which we have to do anyway. I also think this is the better way to go given that it is taking awhile to get this ultrasound on the books anyway- I am not comfortable waiting weeks doing nothing for my cat while waiting for that appointment.

Thanks everyone!

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It’s been a few years since I had a thyroid cat, but going straight to radioablation then wasn’t an option–you had to show good response to methimazole first. That may be why you didn’t hear that option from the vet.

It sounds like you have plenty of experience pilling kitties, but if you decide to go with the transdermal methimazole, use it with care. It can transfer to you not just when you administer it but also just when you’re handling your cat. My vet wouldn’t prescribe it due to the risk of impacting my thyroid.

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Unfortunately, yes I do have experience with medicating a cat for an extended period of time. When the other one came home from hospital we had an aresnal of 4-5 medicines am/pm for 8 weeks. It wasn’t fun, but it saved her.

I just got off the phone with our regular vet in the practice and feel 5 million times better. She brought up all the things I had questions about- and I get the sense that maybe a conversation is going to happen between her and the one i spoke to earlier in the week.

That said the long and short of it is that starting off with methimazole is the way to go, recheck in 1-2 months and see where the liver and thyroid values are. She suspects there is something more going on with the liver than just the thyroid (also why the I131 treatment wasn’t brought up) but she wants to see how the treatment does. Coupled with the confirmation that we’d be waiting on this ultrasound appoint for at least a couple of weeks, it doesnt seem right to sit back and wait for that when it may not change the treatment but just add to the list of meds.

I’ll be picking up her meds this afternoon and getting started with it. Start with pills, and if its horrible or there are side effects we can switch to the transdermal stuff, or try liquid. She’s not super hard to pill but she is not great with liquid, so we won’t go there, lol. She won’t eat treats on her own but if i coat the pill in something and then dip it in a touch of water she’ll let me pill her. Our pill coating of choice in the past has been the pill masker stuff w/ Jackson Galaxy’s face on the label. Not the greatest ingredients but it works and takes a very tiny bit of it to work.

Thank you all again for your experiences and advice, I feel like I can breathe a little easier now!


I have been pilling my cat with methimazole for nearly 2 years. She is just fine with it. Still talks to me and doesn’t run when she sees the puller so that is what we do. It takes about 15 seconds.I haven’t found any treats she likes that I could hide it in and it just seems faster to pill her. $18 for a bottle of 100 (2.5 mg) from Chewy.


Someone told me that it had something to do with the cats smelling different when they come back from the vet.

I will also recommend taking a hard look at radio active iodine therapy. We jumped right to it and didn’t bother with the other meds since you have to withdrawal from the thyroid meds for I think 2 weeks before the therapy

Upfront cost is high but less than 2 years of medication. The cat lived for another 7 years after so it def ended up cheaper.

We had several options but chose against MSU and chose a private surgery in a large town because they could show me that they did this often with a high success rate.

There is the possibility that the can make the cat hypothyroid and you’d still need meds, but my boy came out perfect.

Your cat does come home mildly radioactive so make sure you look at aftercare to make sure it is something you can do. For example we had to store his poop for 6 months before we could trash it due to the radiation. Easy to do with a house but maybe harder to do if you had an apartment.

I would also say get the thyroid in order and then look at the liver. My hyperthyroid kitty was having very similar issues to yours that resolved when we got his thyroid in order.

How old was your cat when diagnosed ? Sorry if you said and I missed that part. TIA

You don’t miss it! I forgot to put it. He was 16!

I’m not sure if things are the same as when I had it done - my memory is that Boris was 9, so that would make it 2001 - but because of the radioactivity issues things varied a bit state to state. I was in Danbury CT at the time and there were facilities in CT and NY, similar distances from me, and I remember that the NY facility would have had to hold the cat longer because of tighter controls on his radioactive status. So I went with CT.

At the time the instructions were to keep him inside and use (and flush) flushable litter (they sent me home with Swheatscoop) and Boris said no. I ended up going ahead and letting him out on his usual schedule because I decided that radioactive pee in my yard was less of a potential risk than radioactive pee in my house.

He lived to 21, though he did have CRF and probable chronic pancreatitis after hmm, age 14 maybe? The kidney numbers were slightly elevated and never got worse. Given the 5-year lag time between the radioactive iodine treatment & onset of those conditions I assume it was not related.

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Def might be state related.

We also had a septic system so that could be why they recommended against flushing. I don’t remember why, just that we needed to store the waste long enough so that it would set off the radiation scanners at the dump.

He lived to 23 yo ? That’s excellent !