Hypothyroidism
the commonest endocrine disorder of the dog the acquired naturally occurring condition has not been documented in the cat although the extremely rare congenital form has been described the metabolically active thyroid hormones are L-thyroxine (T4) and L-3,5,3-triiodothyronine (T3) Aetiology Primary congenital agenesis (rare) non-functional thyroid tumour (rare) lymphocytic thyroiditis; the most important cause (approximately 90%), an autoimmune disorder which results in thyroid destruction idiopathic thyroid necrosis and atrophy may represent the end stage of lymphocytic thyroiditis Secondary Less common than primary1 causes (less than 5%) TSH deficiency leading to inadequate stimulation of the thyroid gland with subsequent reduction in the production of thyroid hormone congenital hypopituitarism (usually in association with GH deficiency) pituitary neoplasia (may present with other signs, e.g. diabetes insipidus) Tertiary thyrotropin-releasing hormone (TRH) deficiency results in deficiency of TSH and reduction in thyroid hormone production due to hypothalamic lesions — extremely rare other equally rare causes of hypothyroidism include: iodine deficiency defects in thyroid Read more […]