Leav I, Schiller AL, Rijnberk A, et al.
NEOPLASMIS OF THE HUMNAN- THYROID are a well-studied clinical and pathologic entity. Numerous publications have dealt with their histologic classification and biology. Comparable data concerning thyroid neoplasms in dogs and cats has not been well established, although these tumors have been described in several textbooks and monographs.’ 9 The purposes of the present study are to: a) classifv adenomas and carcinomas of the canine and feline thyroid using specimens from a collection of well-documented cases; b) illustrate gross, microscopic, and ultrastructural features of these tumors; c) review and discuss recent data concerning hvperthyroidism in dogs with carcinoma of the thyroid; d) report for the first time on clinical and morphologic findings in proven cases of medullarv carcinoma of the canine thyroid; e) correlate histologic, ultrastructural, and clinical data so that structural functional relationships may be more clearly understood; and f) discuss and compare these findings with features of human thyroid neoplasms. It is hoped that this wvork will provide oncologists with current information concerning the appearance and biology of thyroid tumors in two domestic animals which share man’s environment.