Cytological Evaluation of canine mammary tumours with fine needle aspiration biopsy technique

Although cytopathology is widely used for early diagnosis of human tumours, it is not commonly performed in veterinary medicine. The aim of the present study was to compare cytological examination after pre-operative fine needle aspiration biopsies from canine mammary tumours (n = 31) with classical histopathology performed after surgery. Among the 26 available aspirates from various and heterogeneous mammary gland tumour masses, 20 exhibited atypical epithelial cells coupled to nucleus and/or chromatin anomalies, mitotic figures or spindle shape cells and were classified as malignant, 3 only showed modified epithelial cells and were considered as malignant suspected and 3 aspirates were considered as benign because epithelial cells appeared uniform. The most frequent histological types of tumours were malignant mixed tumours and adenocarcinomas, mainly tubular and papillary adenocarcinomas. The agreement score between the 2 techniques was 88.5%, the cytologically suspected malignant tumours being malignant by histology. These results suggest that pre-operative cytopathological examination of mammary masses may be helpful in the early malignancy diagnosis and in the therapeutic decision.