Hyperthyroidism is the most common hormonal disease in older cats. Untreated, it causes significant suffering. Treatment dramatically improves quality of life.
Untreated feline hyperthyroidism causes chronic suffering through weight loss despite increased appetite, hypertension causing eye and kidney damage, cardiac hypertrophy leading to heart failure, and hyperactivity that prevents normal rest. Cats become thin, anxious, and physically uncomfortable. The paradox of high appetite with weight loss causes ongoing hunger despite eating. Early diagnosis through routine blood testing in senior cats (over 8 years) and effective treatment dramatically improves both lifespan and quality of life.