Hyperthyroidism is the most common hormonal disease in older cats, and treatment can go two ways: lifelong medication, or a more expensive one-off cure. Oral medication costs around €30–60/month; radioactive iodine or surgery, which cure it, cost between €1,000 and €2,000. Here are the options, what they cost and how a policy that reimburses 100% covers them.
What is feline hyperthyroidism?
The thyroid gland produces too much hormone, which speeds up the cat’s metabolism: it loses weight despite eating a lot, is restless, vomits or drinks more than usual. It is very common in older cats. It is managed with medication and, in many cases, cured with radioactive iodine or surgery.
How much does it cost to treat hyperthyroidism in a cat?
| Treatment | Indicative cost in Spain |
|---|---|
| Methimazole (oral medication, lifelong) | €30 – €60/month + blood tests |
| Radioactive iodine (I-131, curative, one-off) | €1,000 – €1,500 |
| Thyroid surgery (curative) | €1,000 – €2,000 |
| Periodic monitoring blood tests | depends on the case |
Indicative prices; they vary by clinic, region and the treatment option chosen.
Medication or cure: what works out cheaper?
Medication (methimazole) is cheaper at first, but it is for life: €30–60/month plus blood tests add up year after year. Radioactive iodine cures the disease and, over the long term, its cost is roughly equivalent to about two years of medication, so it is usually the cheaper and definitive option. Either way, these are bills a policy that reimburses 100% helps you absorb.
How Petplan covers it
Petplan reimburses 100% of the bill up to €3,100/year, at any vet, with a €45 co-pay. Whether you choose ongoing medication or curative radioactive iodine, you get 100% of the covered cost back. Take out the policy before diagnosis and keep it: pre-existing conditions are excluded by every company.
FAQ
How much does hyperthyroidism medication for a cat cost?
Oral methimazole costs around €30–60 a month, plus monitoring blood tests.
How much does radioactive iodine cost?
Between €1,000 and €1,500 as a one-off; it cures the disease and long-term usually works out cheaper than lifelong medication.
Does insurance cover hyperthyroidism?
Yes, if it is not pre-existing and you keep the policy. With Petplan you get back 100% of the bill up to €3,100/year.
Can it be cured?
Yes: radioactive iodine and surgery remove the tissue causing the disease. Medication controls it but does not cure it.
Indicative prices in Spain (no official scale) updated for 2026; they vary by clinic, region and treatment. Petplan Spain cover. More in the best cat insurance. Sources: feline veterinary guides (AniCura, IODOCAT, cuasveterinaria).
