Research overview: methimazole and antithyroid medical therapy

Methimazole, and its prodrug carbimazole, block thyroid hormone synthesis and remain the most common medical treatment for feline hyperthyroidism, available in oral and transdermal forms. Medical therapy controls rather than cures the disease, requiring lifelong dosing and periodic monitoring, but offers flexibility, reversibility, and a way to assess kidney function before committing to definitive treatment. This overview synthesizes the pharmacology and clinical literature rather than one citation, describing how antithyroid drugs reduce hormone production, why a trial of medication can reveal masked kidney disease before radioiodine or surgery, and the side effects that require monitoring. It matters because medical management is accessible and reversible, making it a practical first step and a long-term option for cats unsuited to definitive cure.