Hyperthyroidism is the most common endocrine disease in older cats and causes significant suffering if undiagnosed, but is highly treatable with medication, diet, or surgery when identified promptly.
Hyperthyroid cats suffer from a constellation of symptoms that progressively worsen if untreated. Weight loss despite ravenous appetite causes chronic hunger; the associated muscle wasting leaves cats frail and uncomfortable. Cardiac effects including hypertension can cause retinal detachment and sudden blindness. Gastrointestinal signs including vomiting create ongoing discomfort. Behavioural changes including restlessness and vocalisation reflect physiological distress. Many owners attribute these signs to normal ageing rather than disease, delaying diagnosis for months or years during which the cat suffers unnecessarily. Annual blood screening for cats over 10 is the most effective way to catch hyperthyroidism early. Treatment dramatically reverses most signs within weeks, restoring quality of life significantly. The welfare case for proactive senior screening is strong and cost-effective.