Thyroid Nodules In Euthyroid Cats: A Matter Of Age Or Time?
Proceedings of the Annual ACVIM 2002
Ferguson DC, Freedman, R.

INTRODUCTION
It has been said that if a person lives long enough, eventually a nodular goiter will develop. Adenomatous hyperplasia or nodular goiter in the cat is similar to nodular goiter in man with a higher frequency amongst the elderly. Rapid autonomous growth may be a stable trait of cells generated during goitrogenesis, but these apparently newly acquired qualities may also be the simple consequence of the more rapid expansion of naturally occurring cell strains with intrinsically short replication rates. A very differentiated function of thyroid tissue involves its ability to synthesize thyroglobulin and organify iodine to produce iodothyronines. This manuscript will examine the current state of knowledge about the pathogenesis of goitrogenesis, focusing on new basic science and clinical information on the progression. Previous reports as well as new data summarized in this report will document cats with thyroid nodules without overt clinical or biochemical evidence of hyperthyroidism. "Silent" or "cold" nodules are well documented in man; however, there also is a higher incidence of thyroid adenocarcinomas which tend to lose the differentiated of hormonogenesis. Alternatively, it is possible that veterinary practitioners are identifying thyroid enlargement prior to its dominance and suppression of normal thyroid tissue. Retrospective studies support the presence of a subset of cats with nodules not inducing clinical hyperthyroidism. Furthermore, new data provided below indicate that early surgical removal of the enlarged thyroid glands is frequently validated by abnormal histopathology.