Hyperthyroidism is the most common endocrine disease of older cats, causing significant welfare impacts if untreated but with excellent outcomes when managed appropriately.
Untreated hyperthyroidism causes progressive deterioration in quality of life through muscle wasting, cardiovascular stress and gastrointestinal disturbance. Annual veterinary check-ups for senior cats enable early detection. Radioactive iodine therapy (I-131) is considered the gold standard treatment as it is curative in over 95% of cases.