Hyperthyroidism is the most common endocrine disease in older cats, affecting quality of life significantly if untreated. Early diagnosis and effective treatment can restore wellbeing for years.
Hyperthyroid cats often suffer for months before diagnosis because the initial signs — increased appetite and activity — are misread as positive health indicators. As the disease progresses, weight loss, restlessness, and hypertension-induced vision loss cause significant suffering. The welfare case for early diagnosis through routine thyroid screening at annual vet checks is strong. Once diagnosed, treatment dramatically improves quality of life within weeks. Medication compliance is challenging in cats; radioactive iodine offers a permanent cure that eliminates the welfare cost of daily tablet struggles. Renal monitoring after treatment is essential to prevent a new welfare problem emerging as the kidneys' workload changes.