Hyperthyroidism is the most common endocrine disorder in older cats, and effective treatment maintains excellent quality of life for many years in most affected individuals.
Feline hyperthyroidism presents a very treatable welfare challenge when diagnosed promptly. Untreated, the condition causes chronic suffering through the multiple systemic effects of excess thyroid hormone — persistent hunger with progressive weight loss, cardiovascular strain, and gastrointestinal disturbance. Many owners attribute early signs to normal aging, delaying diagnosis. Once diagnosed, treatment dramatically improves welfare outcomes for most cats. Radioactive iodine provides a single-treatment cure, eliminating the medication compliance challenges that affect daily pill-giving programs. The welfare consideration in treatment choice involves not only efficacy but also the stress of treatment procedures — hospitalisation for radioactive iodine versus the challenges of daily medication. Individual cat temperament and owner capacity should inform treatment selection.