TG and hypothyroidism: Measurement of serum thyroid hormone concentrations at a single time point in dogs with NTIS demonstrates consistent decreases in total thyroxine (TT4), free thyroxine (fT4), or both, changes that frequently result in an inappropriate diagnosis of hypothyroidism and needless thyroid hormone supplementation in a euthyroid dog.3, 4, 5, 6, 7