Management options for hyperthyroidism include curative treatments (surgical thyroidectomy, radioiodine) and reversible options such as anti-thyroid medications and iodine-restricted food. All options have advantages and disadvantages. The ‘ideal’ treatment is influenced by the patient, the owner, the clinician (eg their surgical skills) and sometimes local factors such as availability of radioiodine. Intercurrent disease is common since hyperthyroidism primarily affects older cats. The prognosis depends on the presence/extent of intercurrent disease and duration/severity of hyperthyroidism. Many cats with hyperthyroidism, including those with significant intercurrent disease, do very well.
Further Reading:
Hyperthyroidism in cats
Hyperthyroidism: radio-iodine treatment | cats
Thyroidectomy technique in cats