Hypothyroidism is one of the most common endocrine disorders in dogs, causing significant reductions in quality of life when undiagnosed, yet it is treatable with inexpensive daily medication.
Hypothyroid dogs experience a systemic energy deficit that affects every body system. The lethargy and cold intolerance represent genuine suffering — affected dogs have reduced capacity to thermoregulate and engage in normal activity. Skin changes including hair loss, recurrent skin infections, and seborrhea are uncomfortable. Behavioral changes including anxiety and aggression in hypothyroid dogs represent neurological effects of thyroid hormone deficiency. Because symptoms develop gradually and are often attributed to aging or lifestyle, diagnosis is frequently delayed by months or years of unnecessary suffering. Once diagnosed, levothyroxine therapy is inexpensive and typically restores normal quality of life within weeks.