Mammary Mixed tumors are one of the most common tumor types in the female canine mammary glands. These tumors exhibit a histological pattern comprising epithelium and mesenchyme, with or without metaplasia, all of them with the capacity to undergo malignant transformation. In most studies, attention is paid to the epithelial component. We analysed the expression of Ki-67, p53 and the presence of AgNORs/nucleus in 17 Benign Mixed Tumors (BMT) and 17 Carcinoma Mixed Type (CMT) using a specific approach of individual tissue elements (epithelial, mesenchymal and cartilage) through tissue microarrays. Ki-67 immunoreaction was nuclear and perinuclear with low intensity but significantly different in epithelial and mesenchymal tissue.p53 had no immunoreaction in any subset of tumors. The AgNOR/nucleus counting was significant lower in the epithelial component of BMT and CMT. However, there was no variation in AgNOR/nucleus count in mesenchymal and cartilage components.
