So what are the treatment options now that your cat has been diagnosed with hyperthyroidism? There are four options available, two of these options provide a cure for the disease, and the other two options provide lifelong management of the disease.
Daily medication
Most cats that are newly diagnosed with hyperthyroidism are started on daily medication. This is administered either via tablets or transdermally (onto the skin).
It’s worth remembering: long-term medication means twice-daily dosing, blood tests every few months, and the possibility of side effects.
Radioiodine — the ‘gold standard’
Radioiodine is widely regarded as the gold standard treatment for hyperthyroidism in both people and cats. A single injection of radioactive iodine-131 targets and destroys overactive thyroid tissue while leaving healthy tissue unaffected. The treatment requires no general anaesthetic and no surgical wound, with cure rates of 95 to 99%.
As the treatment involves radiation, your cat will need to remain hospitalised for a period, typically between two days and two weeks, depending on which centre they go to, to allow the majority of the radioiodine to clear from their system. Once home, certain precautions will need to be followed for a short time afterwards, such as not sleeping in the same room as your cat, limiting time being in close contact and disposing of litter under strict conditions.
Radioiodine is only offered at a few veterinary centres in the UK. Your vet will need to submit a referral, and the centre will usually require recent bloodwork, blood pressure measurement, and in some cases an echocardiogram before your cat can be booked in. At the Feline Hyperthyroid Clinic, Macclesfield, Cheshire, we specialise in curing cats of hyperthyroidism using radioiodine.
Surgery
Removing the affected thyroid gland is a straightforward procedure and it can be curative. It tends to work best when only one gland is overactive. The most common complication 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. This surgery also requires a general anaesthetic, which is higher risk in hyperthyroid cats, which are often geriatric and have co-morbidities (other diseases as well as hyperthyroidism).
Low-iodine diet
Hill’s y/d is a prescription diet specifically formulated with a very low iodine content, because the thyroid gland needs iodine to produce thyroid hormones — by severely restricting iodine intake, we can reduce the amount of hormone the overactive thyroid gland is able to make. It works best when fed exclusively, meaning no other foods, treats, or flavoured medications, as even small amounts of iodine from other sources can undermine its effectiveness. Therefore it is only really appropriate for indoor only cats.
Where to get radioiodine treatment?
Only a handful of centres in the UK are licensed to offer radioiodine – speak to your vet about which centre is closest or most appropriate for your cat.
