Radioiodine (I-131) therapy is the gold-standard curative treatment for feline hyperthyroidism, offering a one-time cure without ongoing medication, but requires hospitalisation that must be managed to minimise stress.
Radioiodine is medically the superior treatment for feline hyperthyroidism, but the welfare cost of prolonged hospitalisation in an unfamiliar environment must be considered for individual cats. Highly anxious cats or those that are very old and frail may experience significant distress during isolation that offsets the benefit of avoiding daily medication. Veterinary facilities offering radioiodine treatment should invest in environmental enrichment, regular human contact from trained staff, and monitoring of stress indicators during hospitalisation. For many cats, however, the one-time cure and elimination of daily medication stress make radioiodine the highest-welfare long-term option.