Our Veterinary Services

Iodine-131 (I-131) Treatment for Feline Hyperthyroidism

A cat’s thyroid glands are vital. However, an overproduction of thyroid hormones (common in older cats) known as hyperthyroidism, which usually results from a benign thyroid gland tumor, can dangerously affect organs, including the heart. If untreated, hyperthyroidism can also lead to high blood pressure and damage to the kidneys, brain, and eyes. The good news is that it’s treatable.

Introducing Iodine-131 (I-131), an effective and easy therapy for hyperthyroidism in cats.

When iodine, which is used by the thyroid gland to produce vital thyroid hormones for normal health, is made radioactive (I-131) and injected into the body it releases radiation which targets and destroys thyroid tumor cells. The result is that in 95% of cases the disease is cured after only one injection.

Only one relatively painless injection with no anesthesia is required.

  • No effect to healthy thyroid tissue.
  • No damage to other tissue or organs.
  • No need for daily medication.


Only one injection, followed by a comfy stay in our monitored radiation ward.

Following examination and recommendation from board-certified internal medicine doctors, treatment for feline hyperthyroidism begins with a single subcutaneous injection – just below the skin – of radioactive iodine (I-131).

While this procedure is generally safe for pets and humans, federal law and radiation guidelines require pets to be quarantined for a few days in a purpose built and licensed radiation ward such as the one we have at ACCESS – Palm Beach County. It’s here where your cat can excrete radioactive material until reaching acceptable levels before returning home.

Don’t worry, they will be kept cozy, comfortable, and monitored day and night by doctors and highly trained veterinary technicians.

Once home, there are a few instructions from our doctors to follow, such as having your cat stay indoors with restricted human contact and the use of clumping or flushable litter for a few weeks. Of course, if you have any questions while at home, we’re always here to help inform you, and to ensure your cat is on the mend and doing well.

Discover more…

Naturally there’s more to Iodine-131 treatment for your cat. To discover more, please do not hesitate to reach out to the doctors lsited below. They’re here for you and your cat!

Kimberly Golden, DVM, DACVIM
Lucía Alvarez, DVM, DACVIM

I-131 Treatment

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