Association of histological features with potential risk factors and survival in canine mammary tumors

Abstract

The epidemiological and clinicopathological features of canine mammary tumors may provide valuable information to facilitate analysis of the behavior of the disease and represent a potential tool for the study of breast cancer in women. The aim of this study was to associate the histological features of canine mammary tumors with potential risk factors and survival. One hundred and seventy-eight mammary tumors were collected from 80 female dogs. The statistical analyses consisted of a series of univariate studies and frequencies of the different study variables, such as a bivariate analysis with the Chi squared test (χ2), a relative risk and Kaplan Meier survival analysis, and a multiple correspondence analysis was used to correlate the tumor’s biological behavior with the dogs’ breed. Most patients were older than 8 years and had at least one malignant tumor, which was usually solitary and measured more than 6 cm; these patients had poor survival. The most frequent tumors were a complex adenoma, benign mixed tumor, carcinoma complex and mixed type carcinoma. The most commonly affected breeds were Poodle, Cocker Spaniel and Dachshund, and the breeds at the highest risk of tumor development were Cocker Spaniel, Labrador Retriever and German Shepherd. Overall, the data indicated that mammary tumors in dogs mainly affected older females with malignant tumors and that there were high mortality and short-term survival rates. However, the most commonly affected breeds were not necessarily the most susceptible. Our data do not support the hypothesis of an increased risk of canine mammary tumors in nulliparous female dogs.