Radioactive Iodine Service (RAI)


Why Should I Bring my Pet to Willows for RAI?

Willows is home to one of the country’s few Specialist-led Radioactive Iodine services, equipped with one the latest and best RAI units in the UK. The service is run by a team of Internal Medicine Specialists who have extensive experience in treating cats with hyperthyroidism.

At Willows we have Specialists across a full range of disciplines including Cardiology and Anaesthesia, supported by a highly trained team of Medicine Nurses to help manage these cats with hyperthyroidism and provide the best possible care for your pet.


What is Radioactive Iodine?

RAI is a form of treatment for hyperthyroidism in cats and is considered to be the safest and most effective treatment for this condition. It is most commonly administered as cats with hyperthyroidism can be difficult to give medications to. Unlike medical therapy, RAI cures hyperthyroidism, and when compared to surgery for hyperthyroidism, RAI is associated with significantly less complications.


What can I Expect if my Cat is Referred to the RAI Service?

All cats referred to the RAI service will have a consultation and examination by an Internal Medicine Specialist. Following this appointment, some diagnostic tests (e.g. blood/urine tests, blood pressure measurement, a heart scan) will be performed to confirm a patient’s suitability to undergo RAI.

Cats undergoing RAI ideally need to be treated with medications initially for a short period, to check for possible complications that could arise following treatment e.g. kidney failure. These medications need to be stopped for two weeks before Radioactive Iodine can be administered. Following administration of the RAI, your cat will need to be hospitalised for a period of 15 days.

RAI is injected under the skin (like a vaccination). The thyroid gland then takes this up so other parts of the body are not affected. The RAI releases a form of radiation which then destroys the over-active thyroid glands and stops it from producing excessive hormone.


What can I Expect if my Cat is Treated with RAI?

A Specialist from the Internal Medicine service will meet you and examine your cat prior to the RAI treatment. Following this appointment, some tests (e.g. blood pressure check, blood tests, heart scan) will be performed to check for complications and to calculate the dose of RAI.




RAI unit


Post-treatment Care

Your cat will need to stay in hospital at Willows for just over two weeks following RAI treatment. This is required by law to minimise people being exposed to the radiation. Our nursing team will look after your cat during this period and update you regularly.

At the time of discharge from the hospital, we will ask you to abide by a few rules including:

  • Keeping your cat inside the house for eight days after discharge
  • Ensure that no children or infants have prolonged contact with your cat
  • Keeping your cat out of the bedrooms (especially overnight)
  • Avoid holding your cat for prolonged periods of time (maximum of 10 minutes)
  • Use flushable cat litter or store this outside of the house for a month.

Long-term Management

Your cat will need to have some follow-up monitoring after the treatment (starting after one month) to make sure the RAI has been successful and there are no complications. These rechecks can be performed at Willows or at your local Veterinary practice.

Radioactive Iodine

Find out more

To assist owners in understanding more about Hyperthyroidism in cats we have put together some information sheets to talk you through Radioactive Iodine Therapy.