Treating Hyperthyroid Cats

Hyperthyroidism is usually manageable and there is a good chance that your cat will return to normal. The aim of treatment is to reduce the level of and ultimately the effects of excessive thyroid hormone.

Treatment options

It is very important that cats diagnosed with hyperthyroidism are treated as soon as possible. The longer a cat is left untreated the more detrimental the effects of the excessive thyroid hormones. Your veterinarian will discuss your pet’s treatment plan with you and together you can decide on the best option for your cat.

The most common treatments options are:

Medical treatment

Medical treatment is used for long-term management of hyperthyroid cats and prior to radioactive iodine treatment or surgery. Drugs that block the manufacture of the thyroid hormones are used to reduce the levels of these hormones back to normal. This resolves the signs of hyperthyroidism and restores your cat to its old self.

Treatment of hyperthyroidism in cats is life-long. Read more about medication for the management of hyperthyroidism in cats.

Radioactive Iodine

Radioactive iodine treatment requires specialized facilities and hospitalization. It is the most effective treatment in cases with malignant thyroid tumors. It can however result in hypothyroidism – which may require supplementation of thyroid hormones.


Surgical thyroidectomy involves the removal of one or both lobes of the thyroid gland. Cats usually undergo 2-4 weeks of medical treatment to improve their condition and minimize the potential complications, such as heart irregularities. This also helps to reduce the risk of anesthesia.

Surgery is curative in many cases, but hyperthyroidism recurs in up to one-third of cases due to disease in the other thyroid gland or ectopic tissue. Other complications include anesthetic risk, kidney problems, and surgical complications.


Iodine is necessary for the proper functioning of the thyroid gland and the production of thyroid hormones.

Dietary iodine restriction may be an option for cats that can be fed this type of diet exclusively. The long-term consequences of dietary iodine restriction at a cellular level in cats are not clear.

norwegian forest cat

The aim of treatment is to reduce the level of and ultimately the effects of excessive thyroid hormone.