Hyperthyroidism is the most common hormonal disorder in older cats, causing significant discomfort and health problems. Early diagnosis and appropriate treatment are essential for affected cat welfare.
Feline hyperthyroidism causes a distinctive pattern of welfare harm: the cat experiences constant hunger despite eating well (its metabolism is racing), may have chronic diarrhoea, feels persistently unsettled and anxious, and if untreated develops cardiovascular complications that cause breathlessness and distress. Because the changes are gradual and some — like increased appetite — seem positive, owners often miss the diagnosis for months or years. Routine veterinary health checks for cats over 8 years of age, including thyroid palpation and blood testing, enable early diagnosis before secondary organ damage occurs. Treatment options — medication, radioactive iodine, or surgery — allow most cats to return to good quality of life with appropriate management.