Hypothyroidism is common in dogs and causes significant welfare impairment from metabolic slowing, but responds excellently to simple daily medication.
Dogs with undiagnosed hypothyroidism suffer from metabolic slowing that causes fatigue, obesity, skin disease, and cold intolerance. The condition develops insidiously with owners often attributing signs to ageing rather than disease. Correct diagnosis followed by daily levothyroxine treatment reverses most signs within weeks. Owners of treated dogs consistently report dramatic improvement in vitality and behaviour, revealing the significant welfare burden the untreated condition created. The welfare case for screening susceptible breeds is strong given the simple, effective, and well-tolerated treatment available.