hyperthyroidism treatments for cats

woman kissing cat | Hyperthyroidism treatments for cats | Petplan
Posted by Dr. Rebecca Jackson on Apr 23 2013

In a previous blog, we discussed the basics of hyperthyroidism in cats. Today, we are going to discuss some of the treatment options for hyperthyroidism.

First and foremost, how do pet parents and veterinarians treat this disease? Fortunately, treatment is relatively straightforward and most cats respond very well. The three most common options include:

1. Medication, known by its generic name as methimazole

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2. Surgery

3. Radioactive iodine (I-131)

Let’s chat a little more about each of these options.


This is a daily medication that your cat will need to take for the rest of his life. Most likely, your veterinarian will start with this medication before discussing the other treatment options. If your feline friend is a Houdini with pills, making it virtually impossible to get even the smallest pill into them once a year let alone twice a day, you need have no fear.

Methimazole comes in three very user-friendly forms: pills, liquid or as a transdermal, which is administered as a small amount of lotion that you rub into your cat’s ear. Easy enough, right?

After your vet starts your feline friend on methimazole, there will be follow-up blood tests to make sure that you are using the correct dose, and to ensure that your cat is responding appropriately. If all is going well, you can continue this treatment for the rest of your cat’s long and healthy life! If medicating your cat is really difficult, or you want a more permanent solution, your vet may talk to you about two other options.

Surgical options for treating hyperthyroidism in cats

This involves your vet or a veterinary surgeon surgically removing all or part of your cat’s thyroid gland. This is a more permanent solution to the hyperthyroidism afflicting your feline friend, but it doesn’t come without its own potential complications and after-care. Make sure you thoroughly understand the possible risks to this surgery (in other words, don’t hesitate to ask your vet lots of questions) before pursuing this option.

Radioactive Iodine (I-131)

This procedure involves your cat receiving an injection of radioactive iodine I-131 and staying in the hospital for a few days while the substance clears from your cat’s system. This treatment is only available in certain facilities (due to the use of a radioactive substance, its use and your cat’s aftercare are tightly regulated). Radioactive iodine is like a seek-and-destroy missile. It targets the diseased tissue in your cat’s thyroid gland and destroys it. This therapy (unlike surgery) only destroys the bad tissue, sparing the healthy thyroid tissue.

Most cats respond very well to this therapy, and rarely need future treatment. This option is not for every feline with hyperthyroidism, nor every pet parent, so make sure you discuss this option with your veterinarian as well as the facility your cat is referred to receive the therapy before you sign up!

So, we have discussed the clinical signs your cat may exhibit if they are hyperthyroid, the diagnostics involved in determining if your cat is hyperthyroid, and we have discussed the therapy options that are available - all of which are able to be covered by your cat insurance policy from Petplan.

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