Canine mammary cancer (CMC) is one of the most common neoplasms in intact females in comparison to other species. Several risk factors have
been identified, including breed, genetic predisposition, age, reproductive history, hormonal influence, diet, and body condition, in addition to previous lesions to the mammary gland, such as mammary atypical hyperplasia. An understanding of the genetic markers for the disease and a clinical approach are important for establishing a specific therapy that can allow adequate patient survivorship. Overexpression of the HER-2 gene in canines and humans is associated with a poor clinical prognosis, mainly short survivorship, although the clinical relationship is not clear. The incidence of HER-2 in female dogs can range from 29.7% to 38%. However, overexpression of HER-2 is not necessarily associated with malignancy processes of the mammary tissue, although it participates in cellular proliferation. Finally, canines remain one of the most important models for comparative oncology
with humans due to the great similarity in the spontaneous presentation
and development of cancer, and in the high homology in the amino acid sequence.
Booster immunizations with DNA plasmids encoding HER-2/neu prevent spontaneous mammary cancer in HER-2/neu transgenic mice over life span
