Radioactive iodine (I-131) is the gold-standard treatment for feline hyperthyroidism. At Takurua Vets we offer this advanced therapy on-site, giving cats a safe, effective and often permanent cure with a single injection.
Hyperthyroidism is caused by overactive thyroid tissue producing excess hormone. Over time this places strain on the heart, kidneys and other organs. While medication or prescription diets can manage the condition, I-131 directly targets the abnormal thyroid cells and resolves the disease in 95-98% of cases, without ongoing daily treatment.
Hyperthyroidism can be managed in several ways: radioactive iodine, anti-thyroid medication, iodine-restricted diet, and occasionally surgery. The right option depends on whether the diagnosis is secure, how stable the cat is, what kidney and blood-pressure information we have, and what the family can realistically manage.
I-131 is often the best long-term option for a suitable stable cat, but medication can be valuable while we learn how the kidneys respond, when the cat needs stabilisation, or when a permanent treatment is not yet the right step.
Anti-thyroid medication can be an effective way to manage hyperthyroidism, particularly when owners want a non-curative option or when a cat needs stabilisation before longer-term treatment decisions are made. Medication does not remove the abnormal thyroid tissue, so it usually needs to be given on an ongoing basis.
Many cats are now treated with I-131 because it offers a curative solution in the majority of cases without the need for surgery or anaesthesia. The treatment is delivered as a painless single injection, similar to a vaccination, and once cured most cats no longer require daily medication. When cats are appropriately selected, side effects are minimal, and as thyroid levels stabilise they often feel brighter, calmer, and return to their normal behaviour.
Your cat is admitted to Takurua Vets and receives a small injection of radioactive iodine under the skin. After treatment, they stay in our purpose-built isolation ward for around 7 days while the radioactivity naturally decreases to safe levels.
Our team monitors your cat closely throughout their stay and ensures they are comfortable, calm and well cared for.
If you’d like to understand what the process looks like before making a decision, you can watch our walkthrough video showing our facilities, isolation ward, and how cats are cared for during treatment.
When your cat comes home, the radiation level has fallen enough for home care under specific instructions, but temporary precautions may still apply. These instructions protect people, other pets and waste handlers while the last low levels of radioactive iodine continue to leave the body.
Most aftercare is practical rather than complicated: follow the discharge instructions, manage litter as advised, limit prolonged close contact for the stated period, and arrange the recommended follow-up blood testing so we can check thyroid and kidney response.
Does my cat need anaesthesia?
No. The injection is painless and does not require sedation.
Is I-131 safe?
Yes. Side effects are uncommon. Some cats may develop mild hypothyroidism, which is usually temporary or easily managed.
What about kidney disease?
Hyperthyroidism can mask underlying kidney disease. Treating the thyroid condition is still recommended, as leaving it unmanaged places additional strain on the kidneys.
How much does treatment cost?
The current cost at Takurua Vets is $1500, including the admit consult, treatment and 7-day isolation stay. Blood tests are usually arranged with your regular vet clinic.
Can all cats receive I-131?
Most can, but a health assessment is required. Please contact us to discuss whether your cat is a suitable candidate.
Start with the page that matches the decision in front of you. Some families are still trying to understand the diagnosis. Others need to compare treatment options, prepare for I-131 admission, or work through kidney and blood-pressure questions before choosing a permanent treatment.
A plain-language explanation of what the thyroid does, why older cats lose weight, and why treatment matters.
Use this when the key questions are blood testing, kidney values, urine testing, blood pressure or follow-up after treatment.
Compare I-131, medication, iodine-restricted diet, surgery and monitoring decisions.
Understand admission, isolation, radiation-safety precautions, coming home and follow-up after radioiodine treatment.
Read client-friendly summaries of current feline hyperthyroidism guidance, I-131 outcome studies and New Zealand radiation safety context.
Whether you are a cat owner considering treatment or a veterinarian looking to refer, our team is happy to talk through the process and answer any questions.
I-131 is available by referral. We welcome discussion on individual cases and will coordinate medication withdrawal and admission directly with clients.
Please contact the clinic if you would like to refer a patient or discuss suitability.
