Hyperthyroid cat,methimazole and I131 treatment

MamaKat9

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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.
 

FeebysOwner

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Hi M MamaKat9 ! Feeby (16+ yo) was recently diagnosed with H-T (hyperthyroidism). She is on a 1.25 mg dose twice a day and so far so good. I crush her pills into a lickable treat (Applaws, Tiki Cat Stix, Wholehearted, Vitakraft, Inaba Churu, to name a few) and she eats the meds without issue. I have also used Tiki Cat Mousse, the 'juice' from canned tuna or chicken in water, and baby food meats (Gerber Stage 2 or Beechnut) for various med treatments. So, you might consider any of these options with the pills until you decide what to do next.

I haven't personally heard of a 5 year prognosis for cats with H-T, but even with the meds the tumor(s) on the thyroid do continue to grow, so there are issues around that aspect alone. However, having a treatment for H-T does sometimes expose kidney issues that were masked by the hyperthyroidism condition. There is a forum specifically related to H-T cats, as well as a very informative web site that you might want to look into (see links below - both are free to access).

There are also a number of members on here who have used I131 treatment and are very glad they did - so, I hope they will respond as well. I have yet to decide if I want to take Feeby down this path.

[email protected] | Home
Animal Endocrine Clinic | Where science and compassion cure
 

molly92

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I LOVE the I-131 treatment. The hardest part of it is usually the cost (although less than methimazole over 5 years I believe) and the overnight stay. Otherwise, it's very safe, very reliable, and a complete cure.

Hyperthyroidism is one of the few diseases with such an easy cure, actually. Since the thyroid is the only part of the body that uses iodine, injecting "poisonous" (radioactive) iodine ensures that only the overactive thyroid cells get killed off and the rest of the body is completely untouched.

I did the I-131 with my senior kitty Wendy. She only lived about 18 months afterwards because she was already very old and had multiple health conditions, but it was definitely worth it to make her more comfortable for those 18 months. I was able to pick her up after 2 nights at the vet because she passed the radioactive iodine so quickly. She was immediately different when she came home-her heart didn't feel like it was beating out of her chest anymore, and she was a lot calmer in general. No side effects! TSH levels were normal for the rest of her life after that.
 

WMM201

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I LOVE the I-131 treatment. The hardest part of it is usually the cost (although less than methimazole over 5 years I believe) and the overnight stay. Otherwise, it's very safe, very reliable, and a complete cure.

Hyperthyroidism is one of the few diseases with such an easy cure, actually. Since the thyroid is the only part of the body that uses iodine, injecting "poisonous" (radioactive) iodine ensures that only the overactive thyroid cells get killed off and the rest of the body is completely untouched.

I did the I-131 with my senior kitty Wendy. She only lived about 18 months afterwards because she was already very old and had multiple health conditions, but it was definitely worth it to make her more comfortable for those 18 months. I was able to pick her up after 2 nights at the vet because she passed the radioactive iodine so quickly. She was immediately different when she came home-her heart didn't feel like it was beating out of her chest anymore, and she was a lot calmer in general. No side effects! TSH levels were normal for the rest of her life after that.
Hi molly92 molly92 I read on another thread that your Wendy had CDK before her I-131 treatment. My cat Mumu is only about 8 years old, and was staged at IRIS stage II, and was diagnosed yesterday with hyperthyroidism. We're starting her on the ear gel methimazole, but I'd like to get her the radioiodine therapy if her kidneys can handle it. Her vet said that her recent kidney numbers have been good, so I'm hoping that treating her hyperthyroidism won't unmask really bad problems. How did it work out with Wendy? Did treating the hyperthryoid with I-131 lead to a major decline in her CKD?
 

molly92

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Hi molly92 molly92 I read on another thread that your Wendy had CDK before her I-131 treatment. My cat Mumu is only about 8 years old, and was staged at IRIS stage II, and was diagnosed yesterday with hyperthyroidism. We're starting her on the ear gel methimazole, but I'd like to get her the radioiodine therapy if her kidneys can handle it. Her vet said that her recent kidney numbers have been good, so I'm hoping that treating her hyperthyroidism won't unmask really bad problems. How did it work out with Wendy? Did treating the hyperthryoid with I-131 lead to a major decline in her CKD?
Yes, she did have CKD, but her numbers didn't get much worse after I-131 treatment. Now, it can sometimes be really difficult to gauge how bad CKD is from numbers alone-sometimes they don't get that high even though the cat very clearly has symptoms of CKD. But at any rate, Wendy's only got a little bit higher, and we were watching very closely. It looked like it could even have been due to just the gradual progression of CKD over time, not necessarily from the I-131.

That won't be the case for every cat. Even so, hyperthyroidism doesn't protect the kidneys from kidney disease. Kidney cells are still dying off at the same rate regardless. The ones that are left are just more active with hypothyroidism, essentially. But the hyperthyroidism or lack of it doesn't change how much of the kidney is intact. Hyperthyroidism doesn't slow down the amount of kidney damage or extend the life of the kidneys, so for me it really makes sense to go ahead and treat it. Plus, with CKD you need to be careful with diet, and if the numbers are artificially low from hyperthyroidism, then you might not realize how vigilant you need to be about food.

I don't think I can really know how bad Wendy's kidney disease was. I only adopted her at 15 or 16, so who knows what she was like when she was younger, but she was a mess since the day I got her! She'd had a rough life and age really took its toll on her all around. She had a lot of spirit and was definitely a fighter, though! I don't think she would have lasted so long if she wasn't.

Anyway, what I mean to say is I don't think she died of kidney disease specifically, just more like everything was old and tired and slowly stopped working. My goal with her veterinary care was always focused on making her more comfortable, not necessarily extending her lifespan. I do feel like she only died because she was ready, and not from any tragedy in particular.

An 8 year old cat is a different story! She could definitely live many, many more years pretty normally. In that case I think it makes even more sense to do the I-131. It will only get worse over time, so you might as well take care of it for good at the start.

Kidney disease is, as you know, much trickier. There are so many variables and things you can try to slow progression and lessen symptoms, but I wouldn't say I understand more than the basics. Fortunately there are a lot of resources out there and people sharing their experiences and advice.

I do hope everything goes well with Mumu!
 

WMM201

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Thanks so much for this great information, molly92 molly92 . I also just want my cat to have the best quality of life. Aside from two bad crashes that her vets said we're caused by ckd, Mumu has been largely symptom free (some litter box issues now and then). I think after the month of medication, if her kidney numbers look good, I will get the I-131 treatment for her. I saw that Wendy got her treatment from MSU. I am also in Michigan, but I think my vet would refer to Exclusively Cats Hospital. Would you recommend MSU again? Since Mumu is a very small cat, 7.8 lbs, I am worried about her getting too high a dose and making her hypothyroid and damaging her kidneys that way. I will need to talk to my vet about all this as we get further along, of course, but I'd really love to know if you feel good about the MSU team as an option.
 

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Hi M MamaKat9 and W WMM201 ,
I'm one of those who went through the I-131 process with my cat back in 2017.
It was one of the best thing I did in my life. Just like you, I wanted to spare my cat from the bad effects of the Methimazole on her system, so I pushed for having her treated with the radio-iodine.
She was held at the facility for four nights and then she was able to come back home with us. We were instructed on the precautions to observe while the radiations were still a bit high in my cat, but I completely disregarded them.
I'm not telling you that others should do what I did, but just to tell you that I didn't want to put my cat under a further stress of being isolated after what she had been through at the facility.

I would do that again a million times. It worked perfectly.
 

WMM201

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Hi M MamaKat9 and W WMM201 ,
I'm one of those who went through the I-131 process with my cat back in 2017.
It was one of the best thing I did in my life. Just like you, I wanted to spare my cat from the bad effects of the Methimazole on her system, so I pushed for having her treated with the radio-iodine.
She was held at the facility for four nights and then she was able to come back home with us. We were instructed on the precautions to observe while the radiations were still a bit high in my cat, but I completely disregarded them.
I'm not telling you that others should do what I did, but just to tell you that I didn't want to put my cat under a further stress of being isolated after what she had been through at the facility.

I would do that again a million times. It worked perfectly.
I have been reading your posts on the different hyperthyroid threads, Antonio65 Antonio65 , and I learned so much! I really want to get my cat the permanent treatment, too. Right now, we're doing the drug trial to see if her kidney function does suffer, and if it doesn't, I'm planning to get her the I-131 treatment at the earliest opportunity. Like molly92 molly92 said, I'd rather just have to watch one set of organs for Mumu's health than all of them. Mumu also has arthritis, and the gabapentin she takes for pain also isn't great long term, but in the US we don't have a lot of other options. Another reason to get her hyperthyroid treated permanently as soon as it looks safe, in my mind!
 

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Personally I do not recommend MSU! I mean, they're fine if you don't have another good option, but they could do so much better. They actually lost my appointment the first time I made it, and fortunately I called a few days before to ask a question and found out, otherwise I would have driven all that way to not even be seen! And of course, they don't do scintigraphy first and I had to be very persistent to get the dose negotiated down from 4 to 3 miCuries. Which was probably still unnecessarily high. And, I can't imagine that their communication has gotten better under COVID restrictions...

It did work and Wendy was fine, so we got what we needed, but if I ever need to again I'm going to look elsewhere. I don't know anything about Exclusively Cat, but I think it's likely that a more customer-focused business than a school might do better.
 

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Personally I do not recommend MSU! I mean, they're fine if you don't have another good option, but they could do so much better. They actually lost my appointment the first time I made it, and fortunately I called a few days before to ask a question and found out, otherwise I would have driven all that way to not even be seen! And of course, they don't do scintigraphy first and I had to be very persistent to get the dose negotiated down from 4 to 3 miCuries. Which was probably still unnecessarily high. And, I can't imagine that their communication has gotten better under COVID restrictions...

It did work and Wendy was fine, so we got what we needed, but if I ever need to again I'm going to look elsewhere. I don't know anything about Exclusively Cat, but I think it's likely that a more customer-focused business than a school might do better.
Thank you so much! I have been googling around to see what places offer I-131 therapy and then which of those offer scintigraphy, and I haven't really turned up any that specifically say they do scintigraphy, even the Exclusively Cats hospital. I guess I'll ask my vet about it. I was looking at Mumu's test results, and her T4 was at 5.5, which apparently is on the high end of the scale. Given her CKD, small size, but high numbers, I really hope to find a place that knows what its doing!
 

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W WMM201 ,
Be adamant on the scintigraphy, it is absolutely important to precidely assess the dosage of I-131 to be injected and get the best result with the least dose possible.
As for the methimazole, consider applying a transdermal gel rather than administering pills to avoid side effects on the GI tract of Mumu.
 
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MamaKat9

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Hi molly92 molly92 I read on another thread that your Wendy had CDK before her I-131 treatment. My cat Mumu is only about 8 years old, and was staged at IRIS stage II, and was diagnosed yesterday with hyperthyroidism. We're starting her on the ear gel methimazole, but I'd like to get her the radioiodine therapy if her kidneys can handle it. Her vet said that her recent kidney numbers have been good, so I'm hoping that treating her hyperthyroidism won't unmask really bad problems. How did it work out with Wendy? Did treating the hyperthryoid with I-131 lead to a major decline in her CKD?
I have been reading your posts on the different hyperthyroid threads, Antonio65 Antonio65 , and I learned so much! I really want to get my cat the permanent treatment, too. Right now, we're doing the drug trial to see if her kidney function does suffer, and if it doesn't, I'm planning to get her the I-131 treatment at the earliest opportunity. Like molly92 molly92 said, I'd rather just have to watch one set of organs for Mumu's health than all of them. Mumu also has arthritis, and the gabapentin she takes for pain also isn't great long term, but in the US we don't have a lot of other options. Another reason to get her hyperthyroid treated permanently as soon as it looks safe, in my mind!
Hello, I decided to go ahead with the I131 treatment. One month out and things seem ok. I was more worried about the hyperthyroid medication since even in HUMANs it is a concern for liver and kidney function and cats have more sensitive organs. (same exact medication used in humans). The medications for HYPOthyroid are NOT known to cause as much stress on the organs as they are synthetic hormone replacement of hormones that are MEANT to be there. So while I hope that my Smoke does not wind up HYPOthyroid after the I131 treatment, I am less worried about that than about all of the digestive upset and the personality change Smoke experienced from being on the methimazole for a month and a half. I hope that your Mumu can undergo the treatment and that all turns out good for her. Smoke gets his first follow up bloodwork/urinalysis next week. I'm crossing my fingers!!!
 

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W WMM201 ,
Be adamant on the scintigraphy, it is absolutely important to precidely assess the dosage of I-131 to be injected and get the best result with the least dose possible.
As for the methimazole, consider applying a transdermal gel rather than administering pills to avoid side effects on the GI tract of Mumu.
Antonio65 Antonio65 I got the transdermal gel for Mumu as the first option. Mumu refuses pills entirely now, after putting up with allergy medication for half a year, so all her medicine has to be transdermal or compounded liquids. It is pricey but so worth it! I am calling the vet today to see if I can give a lower dose of gel, from 2.5 to 1.25 mg twice daily. I really hope to find a place for the scintigraphy, when we get to the I-131 treatment phase (which I hope will be in a few months once we see how her kidneys are with the medication). I may have to check treatment centers further away.
 

WMM201

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Hello, I decided to go ahead with the I131 treatment. One month out and things seem ok. I was more worried about the hyperthyroid medication since even in HUMANs it is a concern for liver and kidney function and cats have more sensitive organs. (same exact medication used in humans). The medications for HYPOthyroid are NOT known to cause as much stress on the organs as they are synthetic hormone replacement of hormones that are MEANT to be there. So while I hope that my Smoke does not wind up HYPOthyroid after the I131 treatment, I am less worried about that than about all of the digestive upset and the personality change Smoke experienced from being on the methimazole for a month and a half. I hope that your Mumu can undergo the treatment and that all turns out good for her. Smoke gets his first follow up bloodwork/urinalysis next week. I'm crossing my fingers!!!
I hope Smoke will have great test results! Fingers crossed!
 

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I really hope to find a place for the scintigraphy, when we get to the I-131 treatment phase (which I hope will be in a few months once we see how her kidneys are with the medication). I may have to check treatment centers further away.
Hopefully they will do the scintigraphy and the treatment at the same time, so that they have to sedate Mumu once only.
 

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Hi....i'm very glad you had such a successful I-131 treatment for you cat. I was wondering if you had to give replace thyroid hormone after? thanks.

Hi M MamaKat9 and W WMM201 ,
I'm one of those who went through the I-131 process with my cat back in 2017.
It was one of the best thing I did in my life. Just like you, I wanted to spare my cat from the bad effects of the Methimazole on her system, so I pushed for having her treated with the radio-iodine.
She was held at the facility for four nights and then she was able to come back home with us. We were instructed on the precautions to observe while the radiations were still a bit high in my cat, but I completely disregarded them.
I'm not telling you that others should do what I did, but just to tell you that I didn't want to put my cat under a further stress of being isolated after what she had been through at the facility.

I would do that again a million times. It worked perfectly.
 

FeebysOwner

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Some of the responses that were added here were apparently lost in the data center fire that ruined the TCS server - for the radio-iodine treatment - which a scintigraphy is a MUST, this will help determine what the correct dosage of radio-iodine is appropriate and help to preclude an overdose which can cause hyPOthyroidism - ultimately needing hormone treatment. This was very well explained by Antonio65 Antonio65 before this site went down, and apparently was one of many posts that were lost in the site recovery process.
 
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