Hyperthyroidism is the most common endocrine disorder in older cats and is often mistakenly accepted as normal ageing.
Untreated hyperthyroidism causes significant suffering including rapid weight loss, chronic anxiety, hypertension, and heart disease. Many cats with hyperthyroidism display restlessness, vocalisation, and irritability that reflects genuine distress. The condition is readily treatable, but diagnosis requires the owner to seek veterinary advice rather than attributing signs to old age.