Feline hyperthyroidism is the most common endocrine disorder in older cats, causing significant suffering if undiagnosed, but highly treatable when identified early.
Hyperthyroid cats experience significant and progressive suffering when undiagnosed. The elevated metabolic rate causes chronic hunger despite eating, muscle wasting, and gastrointestinal distress. Hypertension from hyperthyroidism can cause sudden blindness from retinal detachment and neurological damage. The heart enlarges under the increased metabolic demand, leading to potentially fatal cardiac complications. Because the condition develops gradually and some owners attribute weight loss to normal ageing, many cats suffer for extended periods before diagnosis. Once identified and treated appropriately, most cats experience dramatic quality-of-life improvement within weeks, making early detection through routine geriatric blood screening a high-value welfare intervention.