Retrospective Investigation of Canine Skin and Mammary Tumors in Korea

Skin tumors and mammary gland tumors have been shown to be the most common neoplasia in most of the strains of dogs. The risk for tumor development increases significantly with age and the prevalence and distribution are various according to individual tumors. The aim of this study is to classify histopathologically the skin and mammary gland tumors for recent two years, 2005 and 2006. A total of 128 skin and 240 mammary gland samples of dogs were selected that were submitted to National Veterinary Research and Quarantine Service and Kangwon National University from January 1, 2005 to December 31, 2006. The excised tissue were fixed in 10 percent neutral buffered formalin and processed routinely to paraffin wax. Sections were cut at 3 ㎛, stained with haematoxylin and eosin. The slides were examined based on the morphological criteria of M. H. Goldschmidt and W. Misdorp under a light microscope. The age of the dogs ranged from 1 to 19 years with a median of 8.7 years. The mean age of the skin and mammary gland tumors was 7.4 and 9.3 years. 47 (12.8%) were males and 259 (70.4%) were female with a male to female ratio of 0.18. Yorkshire terrier and maltese were more susceptible breeds, accounting for 44.3% of skin and mammary gland tumors. In skin tumors, epithelial, adnexal, and mesenchymal origin tumors were 18 (14.1%), 53 (41.4%), and 57 cases (44.5%), repectively. Among the epithelial, adenexal, and mesenchymal origin tumors, basal cell tumor (8.6%), sebaceous adenoma (15.6%), and histiocytoma (25.0%) were predominant in the incidence rate, respectively. In case of mammary gland tumors, 201 (83.8%) were benign and 39 (16.3%) were malignant with a benign to malignant ratio of 5.15. The most frequent mammary gland tumor was benign mixed tumor (35.0%) followed by mammary adenoma-complex type (31.7%).