Hyperthyroidism is the most common endocrine disease in older cats, causing significant suffering when undiagnosed but highly treatable once identified.
Hyperthyroid cats experience a chronic state of metabolic overactivity — restlessness, insatiable hunger despite weight loss, and cardiovascular strain. Many owners observe behavioral changes including increased vocalization and aggression without connecting them to a treatable medical cause. Regular thyroid screening for senior cats allows early detection before significant organ damage occurs.