Development, Anatomy, Histology, Lymphatic Drainage, Clinical Features, and Cell Differentiation Markers of Canine Mammary Gland Neoplasms

TLDR

Mammary neoplasms are the most common tumor in female dogs, and their clinical features—including age, hormones, breed, diet, obesity, tumor size, and lymph node status—are key prognostic factors. The study aims to describe the embryologic development, normal anatomy, and histology of the canine mammary gland from first estrous through the estrus cycle. The authors performed immunohistochemical evaluation of cell differentiation markers in normal and neoplastic canine mammary glands, compared them to human studies, and explored their prognostic utility. They found that specific cell differentiation markers differ between normal and neoplastic tissues and, when compared to human data, could aid in prognostication of canine mammary neoplasms.

Abstract

Mammary neoplasms are the most common neoplasm in female dogs. This article describes the embryologic development, normal anatomy, and histology of the canine mammary gland from the onset of first estrous and the changes that occur in the mammary gland during the estrus cycle. The clinical features of canine mammary gland tumors and their relation to prognosis are discussed, including age, hormones, breed, diet, and obesity. Additional clinical prognostic factors including clinical presentation, tumor size, and lymph node status at the time of presentation are discussed in relation to diagnosis and tumor staging. Immunohistochemical evaluation of the cell differentiation markers of the normal and neoplastic canine mammary gland is described and compared with similar studies in humans; the ways these markers may be used to assist with the prognosis of canine mammary neoplasms are discussed.