Hyperthyroidism is the most common endocrine disorder in older cats. Effective treatment options dramatically restore quality of life, making early detection a key welfare intervention.
Hyperthyroid cats experience a specific form of suffering that is easy to miss because their appetite is maintained or increased. However, the chronic metabolic acceleration — tachycardia, hypertension, weight loss despite eating, restlessness, and anxiety — represents a welfare deficit that compounds with time. Untreated hyperthyroidism causes secondary cardiac and renal disease that further diminishes quality of life. Treatment dramatically restores welfare: radioiodine achieves permanent cure with minimal treatment stress. The renal complication — unmasking of concurrent CKD after treatment — requires pre-treatment assessment and careful post-treatment monitoring. Early detection through annual thyroid screening in cats over 8 years enables treatment before secondary complications develop.