Please read on. The thyroid gland is located on the dogs trachea, just below the larynx. These two hormones regulate the body's basic metabolism - including control of growth and development and maintenance of protein, carbohydrate, and lipid metabolism. More T4 is produced, however, T3 is the more active form and most of T4 is converted into T3 in the tissues. Only the unbound or free hormones are available for physiologic action.
Hypothyroidism is the most common endocrine disease in dogs.
The majority of cases are due to autoimmune thyroiditis. Idiopathic thyroid atrophy is characterized by loss of thyroid tissue, which is replaced by fat and connective tissue. This differs from lymphocytic thyroiditis, in which inflammatory cells invade and eliminate the thyroid tissue. Clinical signs of hypothyroidism become apparent as the thyroid gland is progressively destroyed. The familial tendency has been demonstrated in Great Danes, Beagles and Borzois.