Radioactive Iodine treatment for feline hyperthyroidism- thoughts please!

[Cammie]

CJ will be 13 in July, she was diagnosed with hyperthyroidism along with a heart murmur and enlarged heart and started thyroid meds in the past month. Her thyroid level is now good. She regained some weight and looks and feels great right now. She has no problem eating the pills in her food, so I’m not having to battle giving her meds. She does still have a grade 3/5 heart murmur. I did not do a new x-ray to see if the enlarged heart is still present but assume that it is since the murmur is still there. I was told the heart murmur and enlargement are likely to resolve once the thyroid is treated but no time frame was given. That’s assuming that the thyroid is the cause of the cardiac issues.

She tested positive on the RenalTech panel last month for developing kidney disease within the next two years. Currently her kidneys are within normal limits and starting the thyroid meds didn’t change anything so the wonky thyroid wasn’t masking any issues there so far.

The radioactive iodine treatment will be at minimum $2275. Since I have current bloodwork and x-rays I can use those within the next 3 weeks, if I wait it will be another $550 or so to get new testing done.

Knowing the probability that there may be looming kidney issues within a shorter time frame, would you spend the $2275 if this was your cat? Or just keep going with the thyroid meds and hope she remains stable on those for the next few years?

This is where I wish I had a crystal ball. If I have her for another 5 years, totally worth the money. If I’m going to lose her within a year or two, definitely not worth the money or the stress for her. Thoughts?

[rubygirl1968]

I can only tell you what I did. Snickers was 15 when she had the I131. She already had kidney disease but it was mild and she met the criteria.

I had her on methimazole for a year prior to treatment but she is not easy to medicate. I had to give up on pills and switch to transdermal.

After about 8 months she started running away from me when I’d go near her and I decided to go for the treatment.

I know we aren’t guaranteed a thing with health, people or pets, but I decided it was worth a shot.

She’s 17 now. Her kidney diseased has worsened, and I’m giving her fluids twice a week now but it was worth it for me.

She regained the weight she lost and I don’t have to stress her out with frequent vet trips to check blood levels and medicating every day.

[Simkie]

What are the kidney values? Is it the sdma that’s elevated? Just how high?

What’s the prognosis on the heart issues?

I recently posted about my hyperthyroid cat here:

Cat bloodwork Q

I have an adult cat that’s hyperthyroid and managed on methimazole. He’s been stable and I’d like to radioablate so asked my vet to run some bloodwork to start that process. It shows some out of range values related to his red cells: [image] [image] The vet is unconcerned because hemoglobin is normal, but I look at this and see a long standing dyscrasia that’s trending up/down. I’ve reached out to another vet I work with to discuss, but do the vets here have any feedback (@Ghazzu ?) I’ve…

I found this paper about iodine treatment really helpful in my decision making:

Predicting outcomes in hyperthyroid cats treated with radioiodine

And that led me to:

https://animalendocrine.com/hypurrcat/hypurrcat/

In your shoes, I’d want more info about the heart issues & when they can be expected to resolve (if at all) before moving forward.

[Cammie]

Thanks for the info on how the treatment worked for Snickers. I hope she keeps doing well for a long time to come.

I’m lucky in that CJ is inhaling her pill at the moment so it makes it a lot easier. Given the positive RenalTech test and her age, the vet is recommending she come in every 6 months for bloodwork regardless of whether I do the I131. It would save me $60 each time for not having to do the extra thyroid panel but I’m still going to be spending a minimum of $300 each visit. And still having stressful vet visits for her unfortunately.

[Cammie]

Her kidney values from Feb to March:

2/15/23-
BUN- 27 (14-36)
Creatinine- 2.0 (0.6-2.4)
SDMA- 10.7 (<15)
BUN/CREAT Ratio- 14 (4-33)
PHOSPHORUS- 4.5 (2.4-8.2)

3/16/23
BUN- 30 (14-36)
Creatinine- 1.7 (0.6-2.4)
SDMA- 10.3 (<15)
BUN/CREAT Ratio- 18 (4-33)
PHOSPHORUS- 3.6 (2.4-8.2)

I’m not getting much helpful information on the heart issue. The assumption is that the murmur and enlargement are from the high thyroid, since there was no murmur a year ago at her physical exam and since both are common side effects from hyperthyroidism. There was a shadow on the x-ray that the vet said could be the enlargement or could be a mass- she recommended sending her for an echocardiogram. I have zero interest in pursuing that- it’s expensive as hell, the wait list is months long and if it is a mass, there is nothing that can be done. I figured if she responded well to the thyroid meds that would give a good indication that it is her thyroid causing the issues. I was hoping at her 3 week check up that the murmur would have resolved or improved but it’s still there, and I’m not getting any solid information on when it typically would be expected to resolve. So that is another factor to consider- I of course am hoping for a horse when hearing those hoofbeats, but with my luck it could be a cancer of the heart zebra.

The clinic that is quoting the $2275 is the equivalent here of the one you linked to- they do the scintigraphy and its the Cadillac of clinics with video monitoring and fancy cat enclosures.

The “cheap” chain place is $1300, but they base the dosage off of their bloodwork and do not do any additional diagnostics.

The expensive place has an opening this Sunday if I wanted to roll the dice and opt for it now while her test results and x-ray are still current. But I’m leaning towards waiting 6 months, do the bloodwork again to see what her thyroid and kidneys are doing and see if the heart murmur is still there. I know everyone on COTH is usually an enabler, but I’m glad to get some rational input from the non-emotionally attached!

[Simkie]

@Cammie

But I’m leaning towards waiting 6 months, do the bloodwork again to see what her thyroid and kidneys are doing and see if the heart murmur is still there.

This is how I’d go. Give the methimazole some time to resolve the heart thing. Does your iodine clinic require any heart screening? I’m fairly certain Peterson does, although his site is so mobile unfriendly, I can’t find that page from my phone.

If there was no pressure on this Sunday, would you be considering moving so quickly?

Oh–also to consider–methimazole needs to be discontinued 7-14 days before ablation. Are you still treating now? That alone might take this weekend off the table?

[Cammie]

I’m cheap by nature , so the only pressure to opt for Sunday would be avoiding the additional costs for more bloodwork/x-rays. But since I will already need to do more bloodwork in 6 months anyway to check her kidneys/thyroid I’ll really only be out the additional costs of more x-rays at that point.

Both clinics here require x-rays no older than 45 days before treatment.

She would have to stop the methimazole today if she was going in on Sunday.

Thank you so much for your advice!

[Fiesta01]

Our cat Dexter had the radioactive iodine treatment when he was 11. It went well, and he bounced back to being his happy self for 4 more years. We then lost him to pancreatitis at 15. It was definitely worth it for us. Jingles for your kitty.

[GraceLikeRain]

A family member did it around age 11 or 12 if memory serves. He’s now 16 and doing really well. She feels that it was the right choice and removed the daily logistics of medication.

[SonnysMom]

My trainer just had an 18 year old cat diagnosed with hyperthyroidism. He has head tumors. Radiocat isn’t really an option for him. The vet has started him on a food for hyperthyroidism. He has only been on it for 1 week. He loves it and has gained a little weight. I had never heard about the food before. I think it is by Hill’s
We had 2 cats that we did the pills for a number of years and opted not to do the radioactive iodine due to age and price. More recently we inherited a cat, Clover, that we did the pills for 11 months. Clover was 18 when we got her.

[Simkie]

Yep, this is Hills Y/D. It’s an iodine deficient food. Because the body needs iodine to build the thyroid hormones, limiting iodine when an excess of hormone is being produced can short circuit that production. It can be very effective for some!

[stargzng386]

I had it done for my cat and it 100% was worth every penny. Her values improved with the meds but she was still thrifty. After treatment it took a few months but she is happier, healthier with the shiniest coat she’s had in years. She also had a heart murmur but normal kidney levels. I’d do it again over and over to see her looking and feeling this good. The understanding from talking to my vet was I kind of had to decide quick. Either stick with meds because if anything popped up worse she wouldn’t be a candidate. Lifespan with meds was 2-3 years whereas with treatment there’s no end date most likely something else will be her decline.

[Cammie]

Thanks for the additional info on other cats and the results. I’ll look into it again and decide when she goes back for another blood test in 5 months to see where she’s at with her kidneys and heart murmur. She’s not a candidate for the Hill’s food with her allergies. She’s avoiding the pill in her food half the time now but I’m still able to easily grab her and pop it down her throat.

My other cat Smudge apparently felt like he was missing out on all the expensive vet bills and is now sick with an undiagnosed gastro issue so at this rate I’ll be broke before I can even consider the treatment for CJ. He’s going to have to go back to vet tomorrow since he’s still feeling blah and not eating. He was borderline on his thyroid numbers at his last check up in Nov so with my luck they’ll both need the radiation done. Maybe I can get a discount if I send them both in together.

[Cammie]

Finally spoke to the main vet today while in there for a follow-up for Smudge. He said he absolutely would recommend the radiation treatment for CJ even with the heart murmur and being in the early stages of kidney disease. And I should go to the expensive place with the thyroid scintigraphy. He said hyperthyroidism can be hard to control in cats and it will be far easier to deal with the kidney disease by itself instead of having to manage the thyroid as well.

So when she goes back in for her bloodwork in 5 months I’ll plan on getting the diagnostics done that will be required and see about setting up an appointment. If her kidney values are still doing ok and her heart looks good I’ll fork over the money for the fancy place. I’ll start saving all my pennies now.

[Simkie]

Sounds like a plan!

My kitty is on the schedule to go to Peterson’s clinic in 3 weeks! He was diagnosed just short of a year ago and has been managed on methimazole with really no issues.

Something that did come as a bit of a surprise is they want him on specific food, it looks like something that has gone through AAFCO feeding trials. Thankfully Wellness is on the list, because he’s not real keen on Fancy Feast or Friskies!

[Cammie]

Good luck with your kitty, please let me know how it goes!
CJ will be toast if they want a specific food, she’s almost certainly going to be allergic to whatever your place is recommending. Lol.

[Simkie]

I’ll keep you posted!

The rx diets are on the list, so I’d guess this clinic would ask you to try one of the hypoallergenic diets, like Hills z/d? The intake doc says Hills, Purina, Royal Canin for rx, and Purina, Friskies, Fancy Feast, Wellness, 9Lives for otc.

They go on to say:
Historically problematic brands: Weruva, Tiki Cat, Merrick, Rachael Ray Nutrish, Instinct, Stella &
Chewy’s, Earthborn…

…and other, typically newer, “boutique” cat food brands that do not have well established nutrition or feeding study histories.

I think they’re just looking to ensure that what you’re feeding has what it says it has and that you’re not shorting the cat on iodine.

Thankfully Wellness is on the list (probably because they’ve done feeding trials) because mine is not a fan of anything else they call okay!

[Cammie]

Great. The only thing she can eat is Stella & Chewy’s rabbit! Of course that would be on their “don’t” list. I haven’t tried any of the hydrolyzed proteins for her and with the kidneys being an issue I have to keep that in mind too. Glad you mentioned the food recommendations, I’ll definitely have to ask about that.

[Simkie]

Royal Canin does make a rabbit option. It’s downright nauseatingly expensive, but it’s out there

https://www.petco.com/shop/en/petcostore/product/royal-canin-veterinary-diet-selected-protein-with-pea-and-rabbit-wet-cat-food

[Simkie]

Hey Cammie, I just wanted to update you on this process! My cat’s appt for treatment was next Tuesday. Their request was labwork (full thyroid panel, cbc, chemistry, urine) a week prior to the appt, after discontinuing methimazole 1-2 weeks prior to labs.

I asked about the best window–if three total weeks without methimazole is better than two, happy to do that–and was told that longer is only necessary for cats with mild hyperthyroidism. Mine was graded as moderate, so two was fine.

I was nervous with how he’d feel without treatment, but so far he’s been fine. Brighter. Doesn’t seem anxious. We’ve upped his wet food to head off weight loss, and he’s held steady.

His bloodwork was yesterday. Heard today that the thyroid clinic now considers him “severely hyperthyroid” with a T4 of over 17. No concerns continuing to treatment, but they anticipate a higher dose of iodine, requiring a longer stay to clear the radiation, so they’d like him in a day earlier.

Their attention to detail gives me a lot of comfort!