So your cat’s been diagnosed, they’re on methimazole or carbimazole, and your vet has started talking about next steps. The medication is doing its job for now – but it’s not a cure, and most owners eventually want something more permanent.

Here’s how the treatment options compare, and where you can actually get them done in and around London.

The medication phase matters

You might think of the tablets as temporary, but this period is doing something useful. Your vet is watching how your cat’s kidneys respond. Hyperthyroidism artificially boosts blood flow to the kidneys, which can hide underlying renal disease. Once you bring the thyroid levels down — whether through drugs, surgery, or radioiodine – kidney problems that were always there can suddenly show up.

If your cat’s kidney values have stayed stable on medication, that’s a green light for permanent treatment. If they’ve crept up, it doesn’t necessarily rule anything out, but it changes the conversation with your specialist.

Worth remembering: long-term medication means twice-daily dosing, blood tests every few months, and the possibility of side effects like vomiting or appetite loss. Some cats handle it fine for years. Others don’t.

Radioiodine — the one most specialists recommend

There’s a reason radioiodine gets called the gold standard, and it’s not just marketing. A single injection of iodine-131 seeks out the overactive thyroid tissue and destroys it. Healthy tissue gets left alone. No general anaesthetic, no surgical wound, and cure rates between 95% and 99%.

The part that’s hard is the stay. UK regulations mean your cat has to remain at the treatment centre while radiation levels drop – that’s anywhere from 4 days to about 2 weeks depending on where you go. You can’t visit. The facilities are purpose-built and the cats are well looked after, but that doesn’t make the wait easy.

Expect to pay somewhere between £2,000 and £3,400. That usually covers the injection and hospital stay, but blood work and follow-up appointments are often billed separately. Your vet will need to submit a referral, and the centre will want recent bloods, blood pressure, and sometimes a heart scan before they’ll book your cat in.

Surgery — a good option in the right circumstances

Removing the affected thyroid gland is a straightforward day procedure and it can cure the problem outright. It tends to work best when only one gland is overactive.
The complication people worry about is damage to the parathyroid glands – they sit right next to the thyroid and control calcium levels. If both thyroid glands need removing, the risk goes up. And even after a successful single-side surgery, the other gland can become a problem down the line.
It’s cheaper than radioiodine – around £700 and up – but that lower price tag doesn’t always tell the full story if your cat ends up needing further treatment later.

Where to get radioiodine treatment near London

Only a handful of centres in the UK are licensed to offer radioiodine. These are the ones within reasonable distance of London — speak to your vet about which might suit your cat best.

• Royal Veterinary College – Hatfield, Hertfordshire → rvc.ac.uk
• Medivet 24 Hour – Enfield, North London → medivet.co.uk
• Anderson Moores Veterinary Specialists – Winchester, Hampshire → andersonmoores.com
• The Hyperthyroid Cat Centre – Wetherby, West Yorkshire → hyperthyroidcatcentre.co.uk