Feline hyperthyroidism is the most common endocrine disease of older cats, requiring long-term management to maintain quality of life and prevent secondary organ damage.
Untreated feline hyperthyroidism causes progressive welfare decline through weight loss, chronic nausea, cardiac stress, and secondary hypertension causing retinal damage. Effective treatment dramatically improves quality of life - often owners describe their cat as returning to a younger, more energetic state. Long-term monitoring is essential as concurrent kidney disease may emerge following treatment.