New tests for the assessment of thyroid function in dogs

As the techniques of thyroid imagery are not suitable for use in veterinary practice, laboratory tests are of special interest in the confirmation of thyroid disease. As many thyroidal function tests exist for use in dogs, but all are controversial, we assessed two new tests which have recently been commercially developed: the canine TSH assay and the canine thyroglobulin autoantibody assay. The TSH values assayed with the DPC kit in dogs were usually under 0.55 ng/1. TSH assay could not totally replace thyroid stimulation with T4 measurement in hypothyroidism but permitted distinction between a thyroidal disease (high TSH) and an extrathyroidal disease (low TSH). TSH should be considered as complementary to thyroid stimulation for the determination of hypothyroidal aetiology. TSH measurement could also be used to confirm pituitary aetiology in nanism (TSH undetectable), and to evaluate the therapeutic efficacy of treatments of hypothyroidism with thyroidal aetiology, the dose being suitable when the TSH value returns to normal.