Evaluation of accuracy of fine needle aspiration cytology for diagnosis of canine mammary tumours: comparative features with human tumours

OBJECTIVE: The authors evaluated the accuracy of the fine needle aspiration cytology technique in the diagnosis of 77 canine mammary gland tumours using the same cytological and histological criteria currently applied to the diagnosis of human breast cancer. METHODS: The study was performed in 73 pure or mixed-breed female dogs submitted to surgical resections of 'mammary tumours'. All cytological smears were stained by routine May-Grunwald-Giemsa and Papanicolaou stains. RESULTS: We obtained a correct cyto-histological correlation in 52/77 cases (67.5%) when all cytopathological examinations were considered, and in 52/56 cases (92.9%) when the inconclusive cases were excluded from the analysis. CONCLUSION: Our results demonstrate that, because of the similarity of the cytological findings in the human and canine mammary gland tumours, it is possible to use the same cytological criteria applied in human pathology for the diagnosis of canine mammary gland tumours.