Immunohistochemical detection of estrogen receptor beta (ERp) and cellular proliferation antigen (Ki-67) in canine mammary tumors

Mammary gland tumors are by far the most commonly found tumors in domestic dogs. Although immunohistochemical methods provide valuable information such as the location and semi-quantitative data of the interested antigens in particular tumors, conventional methods like histopathological diagnosis remain useful and necessary for identification and classification of tumors. In the present study, we combined histopathology with immunohistochemical staining of estrogen receptor beta (ERβ) and Ki-67 in canine mammary gland tumors. Twenty nine dogs with mammary tumors between the ages of 5 and 15 years which underwent surgery at the teaching hospital of Rajiv Gandhi Institute of Veterinary Education and Research (RIVER) were included in this study. The aim of this study was to verify the existence of correlations between biological behaviour and immunohistochemical expression of estrogen receptor β (ERβ) and cell proliferation antigen (Ki-67) in canine mammary tumors. Chi square analysis revealed no statistical association between grade and histological tumor type. Immunoexpression of ERβ was 82% (Number/) in benign and 78% in malignant tumors. Ki-67 immunoexpression in case of benign tumors was 36% and in malignant tumors 39%. There was no significant difference between malignant and benign tumors with respect to the expression of ERβ and Ki-67. Spearman's rank correlation analysis revealed a modest positive correlation between ERβ and Ki-67 LI (r =0.5) of benign tumors and between ERβ and Ki-67 LI (r =0.6786) of malignant tumors. Almost all the benign and malignant tumor types expressed ERP and most of the malignant tumor types were both ERβ+ and Ki-67+.