Hypothyroidism is a common endocrine disorder in dogs; with appropriate levothyroxine treatment, affected dogs recover and maintain excellent quality of life.
Hypothyroid dogs experience a constellation of welfare-compromising symptoms that are often insidious in onset and attributed to ageing. Lethargy, weight gain, and skin changes impair quality of life; neurological manifestations including peripheral neuropathy and vestibular signs occur in severe cases. The paradox is that once diagnosed and treated with levothyroxine, the response is dramatic and the prognosis excellent. Treatment is lifelong but straightforward. The primary welfare concern is delayed diagnosis — owners and vets should maintain a high index of suspicion for hypothyroidism in predisposed breeds showing consistent signs.