Feline Hyperthyroidism

Peterson M.E.

Carnation Research Digest, 1985. 21: p.1-14.


Hyperthyroidism is a multisystemic disorder resulting from excessive circulating concentrations of the thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Feline hyperthyroidism occurs in the middle- to old-aged cats. There is no breed or sex predilection. Functional thyroid adenoma (adenomatous hyperplasia) involving one or both thyroid lobes is the most common cause of feline hyperthyroidism. Thyroid carcinoma rarely causes hyperthyroidism in the cat. Graves’ disease, the most common type of hyperthyroidism in man, is an autoimmune disorder in which circulating antibodies cause diffuse thyroid hyperplasia and stimulate excessive thyroid secretion. Graves’-like disease, with associated exophthalmos does not appear to occur in the cat.