Hyperthyroidism is the most common hormonal disorder in older cats, causing chronic suffering when unrecognised and excellent quality of life when treated appropriately.
Feline hyperthyroidism is simultaneously one of the most common and most treatable causes of chronic suffering in elderly cats. A hyperthyroid cat losing weight despite voracious hunger, experiencing hypertension, cardiac changes and potential blindness from retinal detachment is suffering significantly — yet owners often attribute these changes to normal ageing. Diagnosis requires a simple blood test; treatment restores quality of life dramatically. The welfare tragedy of this condition is not its severity but its invisibility: owners attributing weight loss and restlessness to personality or ageing miss the underlying disease until it is advanced.