Hypothyroidism is the most common endocrine disorder in dogs, causing a wide range of clinical signs that significantly affect quality of life. Diagnosis and treatment dramatically restore wellbeing.
Hypothyroid dogs suffer chronically before diagnosis because the condition develops gradually and signs are often attributed to ageing. Lethargy reduces engagement with normal activities; weight gain causes joint stress; skin disease (seborrhoea, recurrent infections) causes itching and discomfort. The welfare impact is substantial and often underappreciated. The striking response to treatment — increased energy, normalised weight, improved coat — illustrates how much the untreated condition diminishes welfare. Owners and veterinarians who remain alert to the subtle early signs of hypothyroidism, and who pursue confirmation testing rather than dismissing signs as normal ageing, provide an important welfare service.