The Disadvantages of Radioiodine Therapy Treatment for Cats

In treating my hyperthyroidism, we went the "no nukes" route.
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Radioactive iodine therapy is becoming the treatment of choice for felines with hyperthyroidism. However, it may not be the best treatment for your particular cat. Weigh the pros and cons of various treatments and discuss options with your vet.

Radioactive Iodine Therapy

Hyperthyroid cats suffer overactive thyroid glands, circulating too much thyroid hormone through their system and affecting nearly every organ. Radioactive iodine therapy offers a cure through a simple injection that returns thyroid function to normal levels. However, because your cat will be radioactive for several days after receiving the shot, precautions must be taken during and after the treatment. While the treatment is fairly expensive, over the long term it could be cheaper than medication and is on a par with surgical treatment.

Limited Facilities

Not all veterinary facilities perform the procedure. If the nearest facility is far away, there's the stress or travel for both you and Fluffy, as well as possible hotel and other travel expenses. Since you'll have to leave your cat at the facility for several days or more, it's not a question of dropping him off at a distant veterinary hospital and then picking him up the next day. It requires two round-trips for you.


If your cat requires daily medications for issues other than hyperthyroidism, he's not a candidate for radioactive iodine therapy. Only the bare necessities—food and water and quick litter cleanups—are provided by veterinary technicians during your cat's hospital stay. He's radioactive, so it's not safe even for humans wearing protective clothing to spend too much time around him. Giving him medication once or twice a day isn't an option, although if it's a medication that can be mixed in with his food, it's something you could discuss with the veterinary staff at the facility.


You can't visit Fluffy during his stay at the veterinary facility. If you can't bear to be away from him, or if he becomes very stressed or frightened when you're not around, that isolation could be difficult. Once his radiation levels come down and you can bring him home, you still have to keep him away from young children and pregnant women, as he'll pass small amounts of radioactive iodine through his urine for approximately two weeks. He also can't sleep with you during that time, and the facility will inform you about special arrangements you'll have to make for disposing of his litter.


If radioactive iodine therapy won't work for you and your cat, alternatives are available. Your cat can receive methimazole, a medication that inhibits thyroid hormone production. You'll have to give him this drug twice daily for the rest of his life, which treats but doesn't cure the condition. Fluffy might be a candidate for a thyroidectomy, surgery to remove the thyroid glands, which usually results in a cure. It might not be an option for a frail cat who shouldn't undergo anesthesia. A prescription diet is available that lowers thyroid hormone, but for it to work your cat can't ever eat any other food.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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