There are three common interventions prescribed for cats with hyperthyroidism: administration of radioactive-iodine therapy, surgical removal of the thyroid gland, and management with medication.
Radioactive Iodine Therapy
Radioactive iodine therapy is often the first line of treatment for cats with hyperthyroidism. For this therapy, your veterinarian will inject your cat with a radioactive iodine solution, which targets and destroys affected thyroid tissue. This treatment usually corrects hyperthyroidism in cats within a month. This treatment cures hyperthyroidism in 95 percent of cats, however, your cat will require hospitalization for approximately three days while her levels of radiation fall. After three days she will be safe to handle again.
Surgery
Another solution available for cats with hyperthyroidism is surgical removal of the entire thyroid gland. While this procedure is generally recognized as safe, it does pose a threat to the nearby parathyroid gland. Like radioactive-iodine therapy, surgery is a curative solution to hyperthyroidism in cats.
Medication
The final mode of treatment for hyperthyroidism in cats is medication. Unlike radioactive-iodine therapy and surgery, medication does not cure hyperthyroidism. Rather, it reduces the production of thyroid hormones by the thyroid gland for the long-term management of hyperthyroidism. Medication for hyperthyroidism in cats is inexpensive, but requires administration multiple times per day and often causes unpleasant side effects. It also taxes organ systems that might already be affected by hyperthyroidism, such as the kidneys. Your veterinarian should monitor your cat's kidney function while she is taking antithyroid medication.