Radioactive Iodine therapy (I 131) is a very safe and effective treatment for feline hyperthyroidism that has an approximately 95% cure rate and no direct side effects for your cat.

The treatment is very simple in that we just administer a single radioactive iodine capsule by mouth and the radiation subsequently “homes in” on the overactive thyroid tissue and preferentially destroys this.

Whilst we carefully assess your cat before the treatment, we cannot guarantee that all the symptoms we are seeing are caused by the hyperthyroidism and there is small chance that symptoms caused by another disease can continue even after successful treatment of the hyperthyroidism.

There is a small chance (probably less than 10%) that the treatment may cause the thyroid levels to become too low (hypothyroidism). This may require temporary or permanent hormone replacement liquid.

As with any treatment for hyperthyroidism, there is a risk that treatment can worsen kidney function tests. In the vast majority of cases, this is minor and is not significant.
Because of human health concerns, your cat will have to be isolated for 5-10 days with no direct human contact. This means that no medications can be administered.

To reduce the risk of staff exposure to radioactivity, we administer a light sedative to enable the radioactive iodine capsule to be given. There is always a very small risk with any sedation but the protocol that we use is a very safe option for cats with hyperthyroidism.

For a two week period after discharge, your cat will excrete very small amounts of radiation and prolonged close contact will need to be avoided. If this is going to be a problem, then you may need to consider hospitalisation at our hospital or your local vet for that time.

Whilst treatment with tablets and creams may be useful in the short to medium term, for the vast majority of hyperthyroid cats, radioactive iodine treatment is the treatment of choice long term.