Radioactive iodine

Information for cat owners

Everything you need to know about hyperthyroidism in cats and what happens during radioactive iodine treatment.

What is hyperthyroidism?

Hyperthyroidism is a common condition in older cats, usually diagnosed between 10 and 14 years of age. A benign growth on one or both thyroid glands in the neck produces too much thyroid hormone. This speeds up your cat’s metabolism and, if left untreated, can lead to heart disease, high blood pressure, blindness and kidney problems.

Common signs

Weight loss despite a good or increased appetite
Drinking and urinating more
Vomiting or diarrhoea
Restlessness, increased vocalising or crying at night
A poor or unkempt coat
A fast heart rate or heart murmur

Treatment options

There are four ways to manage hyperthyroidism: daily medication, a prescription iodine restricted diet, surgery, or radioactive iodine. Medication and diet control the condition but do not cure it, and must be continued for life. Radioactive iodine is the only permanent option that does not require surgery.

What to expect

Before treatment: your cat will need a check-up and blood tests to confirm the diagnosis and check kidney function. If your cat is on anti-thyroid medication, your vet will advise when to stop it before treatment.
Treatment day: the radioactive iodine is given as a simple injection or capsule. It is painless and no anaesthetic is needed.
Hospital stay: treated cats stay in our specially shielded ward for several days, until their radiation levels are low enough to go home safely. Our team monitors them closely and makes sure they are comfortable and eating well.
Going home: we will give you clear instructions to follow for about two weeks, such as limiting close contact and disposing of litter safely.
Follow up: a blood test is recommended a few months after treatment to confirm your cat’s thyroid levels have returned to normal.

Our team will talk you through timing, costs and your cat’s individual needs before booking.

Frequently asked questions

Is radioactive iodine safe for my cat?

Yes. Treatment is very safe, painless and has no serious side effects for the vast majority of cats.

Can I visit my cat during their stay?

Because of radiation safety regulations, visits are not possible during the hospital stay. We will keep you updated on how your cat is going.

Does my cat need a referral?

You can speak to your regular vet about a referral, or contact us directly and we will help arrange the necessary tests.

Is it expensive?

Radioactive iodine is a one-off cost, and because it usually cures the condition, it can work out comparable to years of medication and blood tests. Contact us for a current quote.