Feline hyperthyroidism is the most common hormonal disorder in older cats, and advances in treatment options including radioiodine therapy now offer the possibility of cure rather than lifelong management, transforming welfare outcomes.
Undiagnosed or inadequately managed hyperthyroidism causes prolonged suffering: the cat is chronically hungry yet losing weight, often anxious, sometimes aggressive, and at risk of blindness from hypertensive retinal detachment. Regular veterinary monitoring of senior cats enables early diagnosis before complications develop. Radioiodine treatment, while requiring temporary isolation, offers a welfare advantage over lifelong daily medication that many cats resist and owners find difficult to administer consistently. For cats where daily medication compliance is poor, radioiodine or surgery may provide better long-term welfare outcomes despite the short-term welfare cost of the procedure.