Veterinary Research Communications, 27 Suppl. 1 (2003) 359–361 © 2003 Kluwer Academic Publishers. Printed in the Netherlands Canine Ovarian Tumours: A Retrospective Study of 49 Cases M. Sforna, C. Brachelente, E. Lepri and L. Mechelli Department of Veterinary Biopathological Sciences, Section of Veterinary Pathology and Hygiene, Faculty of Veterinary Medicine, University of Perugia, 06126 Perugia, Italy * Correspondence: Dipartimento di Scienze Biopatologiche Veterinarie, Sezione di Patologia ed Igiene Veterinaria, Facolta ` di Medicina Veterinaria, Universita ` di Perugia, via S. Costanzo, 4, 06126, Perugia, Italy E-mail: pgpatvet@unipg.it Keywords: dog, haemangiosarcoma, immunohistochemistry, ovarian tumours Abbreviations: GCT, granulosa cell tumour INTRODUCTION Primary ovarian tumours are relatively uncommon in domestic animals. They may be classified by histogenetic criteria into four major categories: ( 1 ) epithelial, ( 2 ) germ cell, ( 3 ) sex-cord stromal and ( 4 ) mesenchymal tumours. Bitch ovarian tumours are usually epithelial and bilateral, whereas in the cow and mare they are often unilateral and mostly of the sex-cord stromal type. In canine species, the incidence ranges from 1% to 6% and the age of affected animals varies from 5 to 15 years, although granulosa cell tumours (GCTs) and teratomas generally develop in younger animals. A breed predisposition has not been reported, but bull- dogs and boxers seem to show a higher risk. The aim of this study was to evaluate clinical-pathological findings in 49 canine ovarian tumours by means of a retrospective study of bioptic and surgical material. Histopathological and immunohistochemical evaluations were performed to classify these neoplasias according to the World Health Organization criteria (Kennedy et al., 1998). MATERIALS AND METHODS Forty-nine ovarian tumours were selected from the 4770 spontaneous dog neoplasias that were analysed. Some of the dogs were necropsied after either euthanasia or spontaneous death. All tissues were routinely processed and stained with haematoxy- lin and eosin, Mallory’s trichrome stain, PAS and Giemsa. Immunohistochemical detection of cytokeratin, vimentin and CD31 was performed using a two-step technique (streptavidin–biotin–LSAB±Dako) with DAB chromo- gen. In some cases cytological examination was performed on abdominal effusions 359