Radioiodine Treatment for Hyperthyroidism in Cats

Emma Murphy RVN explains more about hyperthyroidism in cats.

Hyperthyroidism is a common illness in older cats that is caused by an overactive thyroid gland. This results in too much of the thyroid hormone being produced, which can cause many clinical symptoms, including:

  • Weight loss
  • Increased appetite
  • Increased thirst
  • Increased activity or irritability
  • Increased heart rate
  • A poor coat

Untreated hyperthyroidism can cause damage to your cat’s heart and kidneys as well as high blood pressure.

Treating Hyperthyroidism

There are a number of options available for treating hyperthyroidism in cats. These treatment options include:

  • Lifelong medication.
  • Diet.
  • Surgery to remove the thyroid glands.
  • Radioactive iodine therapy.

My own cat, Scarlett, was diagnosed with hyperthyroidism following a routine blood test and we had to make a decision on what would be the best course of treatment for her. On of our vets at Pride Veterinary Centre, Caroline Kisielewicz, discussed Scarlett’s results with me and went through each of the treatment options mentioned above.

After weighing up each of the options, I decided that the best treatment for Scarlett would be radioactive iodine treatment. This is because it provides a lifelong cure in around 94% of patients.

Scarlett’s Radioactive Treatment Journey

I was initially apprehensive about it, as following treatment cats are required to stay in a special isolation unit for two weeks. The treatment requires the cat to be sedated and an injection of radioactive iodine liquid is injected under the skin.

In order to have the treatment she needed to have some tests first including a heart scan, blood pressure, blood tests and urine sample to make sure that she was not at risk of becoming seriously ill after going into the radioiodine unit, as they can’t be handled during the isolation period. All of the tests were fine, and we set a date for her treatment.

On her admit day, the medicine nurses went through her normal dietary routine with me and let her have a bed and some favourite toys from home (although nothing that goes into the unit can come back out). I was worried that she wouldn’t settle, eat, use her litter tray, but the first night they rang to say she was doing well, had eaten all her dinner, used the litter tray and was curled up in bed!

During her treatment the nurses went in twice a day to clean, feed and make sure everything was ok. As there are restrictions on the amount of time they can be in the ward, they have a special camera with a screen outside the ward so that they can see the cats in the unit at all times, and talk to them via a microphone. They also have a radio in the ward to provide some home comfort. We had daily updates, and she was settled and happy for the whole two weeks. Once she was ready to come out of radioiodine, she transferred into the cattery’s isolation kennel, as they need to be handled less for a minimum of two weeks post treatment, and have minimal interaction with other pets.

As we couldn’t easily manage this at home, we chose to wait until her radioactivity readings were at a low enough level to be safe. She was allowed short visits, and more things from home to help her settle in, and she was well looked after/spoiled by the nurses caring for her.

Following treatment repeat blood samples are required after one, three and six months to ensure that the treatment has worked and there are no problems. So far these have been fine, and Scarlett is now home and happy.