Anyone have any experience with thyroid problems in cats?

When we ran my Mutty's bloodwork, it came back that she is on the border of concern for her thyroid so we're having another test done.

Does anyone have any experience with this and how is it treated???


Thanks a bunch!

Yep, one of my babies had thyroid problems about 3 years ago. The bloodwork showed it was highly elevated, and we noticed she'd started to lose weight even though her appetite was great.

The usual treatment for hyperthyroid is to start with daily meds, Tapazole. My kitty had an allergic reaction though; the skin above her eyes became bright pink so we discontinued the med.

Another treatment for hyperthyroid is surgical removal of the thyroid, which is not recommended. Fortunately, there is something called I-131, radioiodine. It's a safe, non-invasive *cure*, not just a treatment. The I-131 is injected like an ordinary shot. That's it. The cure rate is very high, around 98% of cats. However, I-131 is expensive, and your kitty must be kept at the vet for at least several days. The time the cat must stay at the animal hospital varies with location - in NJ, it was 4 days. During this time the vet monitors the amount of radioactivity - most of it dissipates within 4 days or so. Once home, you have to carefully dispose of your cat's waste for the next 3 weeks, since the I-131 is excreted this way. The amount of radiation left is tiny by the time your cat comes home, but vets recommend these precautions to be on the safe side.

The I-131 did wonders for my little girl. She started gaining weight back and was soon at her normal weight. No side effects either. It's great not to have to worry about giving meds every day, and even better to know the thyroid problem is cured, not just being controlled.

Good luck with Mutty's test. Hopefully she won't need treatment yet.

KT Lynn, please tell me you have your kitty on thyroid replacement hormone. I-131 destroys the thyroid so they then become hypothryroid and must have hormone replacement. they should also have her T4 status monitored periodically.

I agree that 1-131 is the best treatment. One of my kitty's had a toxic reaction to the tapazole and it was damaging her liver, thus not a long term option for her.

Vets generally want to do a month or so on tapazole before irradiation because hyperthyroidism can cause kidney damage. This is because it increases blood pressure which hyperperfuses the kidneys and damages them. When the thyroid hormone levels are brought back down to normal the blood pressure also decreases, then the kidney damage shows up.

If your kitty is caught early the likelihood of kidney damage so soon is minimal. Long term prognosis is good. This is one of the common kitty diseases that are readily treatable.

Originally Posted by kittymonsters

KT Lynn, please tell me you have your kitty on thyroid replacement hormone. I-131 destroys the thyroid so they then become hypothryroid and must have hormone replacement. they should also have her T4 status monitored periodically.

I agree that 1-131 is the best treatment. One of my kitty's had a toxic reaction to the tapazole and it was damaging her liver, thus not a long term option for her.

Vets generally want to do a month or so on tapazole before irradiation because hyperthyroidism can cause kidney damage. This is because it increases blood pressure which hyperperfuses the kidneys and damages them. When the thyroid hormone levels are brought back down to normal the blood pressure also decreases, then the kidney damage shows up.

If your kitty is caught early the likelihood of kidney damage so soon is minimal. Long term prognosis is good. This is one of the common kitty diseases that are readily treatable.

Click to expand...

Where are you getting your information about thyroid replacement hormones? The majority of hyperthyroid cats treated with I-131 do not need supplementation with thyroid hormones. Radioiodine targets the hyperactive thyroid cells, destroying them. The normal thyroid cells (which are not destroyed in most cases) usually begin to function on their own in 1-3 months, though in some cases it takes 6 months, and occasionally supplementation is needed if the cat's normal thyroid cells don't kick in.

This study indicates that depending on where the tumor is located, 60-83% of cats were not hypothyroid. In this larger study [note: this is a Word document], however, only 2.1% of cats actually needed supplementation with thyroid hormones--not all hypothyroid cats required supplementation since asymptomatic hypothyroidism is not dangerous like hyperthyroidism. Please note the following statement from this study: "In addition, because hypothyroidism may be transient, thyroxine treatment should be withheld until clinical signs of hypothyroidism develop."

For Mutty's human, definitely proceed with the additional testing, but please consider early treatment. Treatment with radioiodine is most effective when done early, before the thyroid tumor has grown substantially and before the excess thyroid hormone has had time to damage the heart, liver, and kidneys. I wish I had had the procedure performed on Spot when I first found him rather than waiting 9 months. Spot had been hyperthyroid a long time by then (he was already hyperthyroid and thin when I found him), and his thyroid resisted the treatment. By the time we tried the second treatment, his heart condition (which was probably not caused by the hyperthyroidism but may have been made worse by it) had worsened and I lost him. Early treatment is the best bet in giving you many more happy healthy years with your cat. While it is expensive up front, the long-term testing and medication is even more so.