RESUMO
Mammary tumors represent the second most common neoplasia in the canine species, where more than 50% of the cases are classified as malignant. The histological classification is used as a prognostic tool. Cadherins and catenins are responsible for cell adhesion and are intrinsic connected with the process of metastasis. E-cadherin expression in canine mammary tissues have been extensively studied. However, the studies with catenins are still scarce in the canine species. This study evaluated 74 canine mammary tissues by assessing the expression of E-cadherin and α, ß and P-120 catenin molecules using the immunohistochemistry technique and their relationship with clinicopathological parameters. Three patterns of expression were identified in this study: membranous, cytoplasmic and both (membranous and cytoplasmic). In benign tumors, more than 80% of the cases had preserved expression and in malignant tumors 20% of the cases had reduced expression. A correlation between E-cadherin and P-120-catenin expression was found as well as a significant relationship between the histological type and the expression of α-catenin in malignant tumors.