Hyperthyroidism is the most common endocrine disease of older cats. Effective management is essential for quality of life in affected animals, and treatment options have expanded significantly.
Untreated hyperthyroidism causes significant chronic suffering through the physiological effects of excess thyroid hormone: heart racing, high blood pressure causing retinal detachment and blindness, weight loss despite constant hunger, and eventual heart failure. Early diagnosis through routine blood testing in older cats is one of the most important welfare interventions in feline medicine. Once diagnosed, treatment significantly improves quality of life — most owners report dramatic behavioral improvement after treatment. The choice of treatment method depends on individual circumstances including severity, concurrent disease, and owner compliance capacity. Regular monitoring after treatment is essential as kidney disease may emerge.