Cutaneous tumors in dogs - A retrospective study of ten years

Abstract

In this study were used 662 samples of skin tumors, from 644 dogs, originating from regions of the State of São Paulo, Brazil, between January 1998 and January 2008. The samples were obtained from necropsies (1.66%) and surgical excision (98.33 %). Twenty-three different types of skin tumors were diagnosed, with some animals affected (1.70%) by more than one morphological type. The mesenchymal tumors were categorized into eight different histological types with great occurrence (53.92%) followed by epithelial tumors (12 types; 35.04%), melanocytic tumors (one type; 6.64%) and hematopoietic tumors (two types; 4.38%). Mastocytoma, histiocytoma, squamous cell carcinoma, fibrosarcoma and melanocytoma were the most common tumors, accounting for just over 50% of all the cutaneous neoplasia. There were 53,27% of females and 46.73% of males; 72.81% of the dogs were purebred, while 27.19% were mongrels. The malignant tumors (59.51%) were more frequent than the benign tumors (40.49%). The occurrences of epithelial, mesenchymal and melanocytic tumors were statistically greater among dogs aged six to eleven years. Hematopoietic tumors were more frequent among animals aged zero to eight years. These results are important for small-animal clinics. They serve as a further tool to direct the diagnosing of cutaneous neoplasia in dogs as rapidly and precisely as possible.