Hyperthyroidism is a common disease of older cats that causes significant suffering if untreated but responds well to several treatment options.
Untreated hyperthyroidism causes progressive weight loss despite ravenous hunger, cardiac disease, hypertension, and systemic organ damage. The chronic nature of untreated disease means prolonged suffering. Radioactive iodine provides a permanent cure, while daily medication manages the condition long-term with careful monitoring.