Hypothyroidism is one of the most common endocrine disorders in dogs and causes multiple welfare harms through reduced metabolic function that respond well to treatment.
Hypothyroidism causes insidious, progressive welfare decline that owners often attribute to normal aging. A dog that is lethargic, cold-intolerant, gaining weight despite normal eating, and developing skin problems may be experiencing significant metabolic dysfunction that is entirely reversible with treatment. The tragedy of undiagnosed hypothyroidism is that a dog may live for months or years with significantly reduced quality of life when simple, inexpensive daily medication would restore full function. Recognizing that lethargy and weight gain in middle-aged dogs warrants investigation rather than acceptance is a key welfare message.