INTRODUCTION: Canine cutaneous mast cell tumor has one of the most recurrent cases in the diagnoses of veterinarians, second only to the breast tumor. Therefore, the importance of knowing and understanding this neoplasm becomes increasingly important and fundamental in the small animal clinic. High-grade mast cell tumors are of paramount importance in studies due to their high malignancy, having rapidly propagating cells, which can have severe anomalies, such as giant cells, also known as gigantocytes. Gigantocytes are formed by the fusion of macrophages, and are observed in cases of high malignancy mast cell tumors, but their cause is still unknown. – OBJECTIVES: This study aims to detect the presence of giant cells, used as a criterion for evaluating high-grade mast cell tumors, according to Kiupel et al. (2011), in 69 animals treated with this neoplasm at the veterinary clinic school of PUCPR (CVE-PUCPR) in the last five years. – MATERIALS AND METHOD: The research was based on information such as age, breed, weight, degree and location of the affections, sex and status of the animal. In cases classified as high grade, the neoplasm was observed in histopathological preparations aiming at the presence of giant cells. The collected data were entered into a spreadsheet and the relative and absolute frequency or percentage distribution of the whole was made. – RESULTS: Through this, one can observe a greater number of female animals, mixed-breed dogs, weighing between 16 and 23 kilos, ten years old and the largest site of involvement being in the pelvic limb region. Most of the cases observed in the survey carried out at CVE for this research were of the second degree, according to Patnaik et al. (1984) and low grade according to Kiupel et al. (2011). – FINAL CONSIDERATIONS: Therefore, all the cases of cutaneous mast cell tumor presenting high degree according to Kiupel had multinucleated giant cells. In this case, we can not exclude a possible correlation between those two factors, which are high degree mast cell tumor and the presence of giant cells.
