Feline hyperthyroidism is the most common endocrine disorder in older cats. Effective treatment options restore quality of life, but each carries different welfare trade-offs.
Untreated hyperthyroidism causes significant chronic suffering — cats experience relentless hunger, anxiety from cardiac arrhythmias, hypertension causing retinal detachment and blindness, and eventual multi-organ failure. Treatment dramatically improves quality of life. Radioactive iodine is curative and stress-free for the cat beyond the isolation period, but requires a specialist facility. Daily oral medication is accessible but stressful for cats that resist pilling, and owner compliance over years is challenging. Surgical thyroidectomy carries anesthetic and parathyroid risk. Iodine-restricted diets require strict dietary compliance — no treats, no hunting — which compromises some cats' quality of life. Weighing these trade-offs with a vet is essential for individualized welfare-centered care.