Mammary neoplasms are described as the third most common type of feline tumor, after haematopoietic and skin tumors, and present a challenge for clinicians because the prognosis for feline mammary tumors ranges from guarded to poor. Thus, it is necessary to define new therapeutic approaches and establish more in-depth knowledge about this disease in felines. The main aspects of the diagnosis, prognosis and treatment of feline mammary neoplasia were discussed, aiming to standardize the criteria and to serve as a guide for pathologists and veterinary clinicians.

Mast cell tumor (MCT) is a frequent cutaneous neoplasm in dogs that is heterogeneous in clinical presentation and biological behavior, with a variable potential for recurrence and metastasis. Accurate prediction of clinical outcomes has been challenging. The study objective was to develop a system for classification of canine MCT according to the mortality risk based on individual assessment of clinical, histologic, immunohistochemical, and molecular features. The study included 149 dogs with a histologic diagnosis of cutaneous or subcutaneous MCT. By univariate analysis, MCT metastasis and related death was significantly associated with clinical stage ( P < .0001, r = -0.610), history of tumor recurrence ( P < .0001, r = -0.550), Patnaik ( P < .0001, r = -0.380) and Kiupel grades ( P < .0001, r = -0.500), predominant organization of neoplastic cells ( P < .0001, r = -0.452), mitotic count ( P < .0001, r = -0.325), Ki-67 labeling index ( P < .0001, r = -0.414), KITr pattern ( P = .02, r = 0.207), and c-KIT mutational status ( P < .0001, r = -0.356). By multivariate analysis with Cox proportional hazard model, only 2 features were independent predictors of overall survival: an amendment of the World Health Organization clinical staging system (hazard ratio [95% CI]: 1.824 [1.210-4.481]; P = .01) and a history of tumor recurrence (hazard ratio [95% CI]: 9.250 [2.158-23.268]; P < .001]. From these results, we propose an amendment of the WHO staging system, a method of risk analysis, and a suggested approach to clinical and laboratory evaluation of dogs with cutaneous MCT.

Mammary neoplasms are the most frequent tumors in female dogs. Of these neoplasms, benign mixed tumors (BMTs) and carcinomas in mixed tumors (CMTs) represent a large proportion of small animal oncology diagnoses. Together with carcinosarcomas (CSs), these three neoplastic entities are characterized by the proliferation of benign or malignant epithelial, myoepithelial, and mesenchymal cells, depending on their histological types. This histological heterogeneity, in addition to their molecular heterogeneity, confers these tumors with distinct biological behavior, which results in the need for different clinical and therapeutic approaches. The present consensual document elucidates the oncological issues related to the diagnosis, prognosis, and treatment of BMTs, CMTs, and CSs of the canine mammary gland.

Background: Presence of tumor markers in serum might be connected to the number of secreting cells and with the stage of the neoplasm. However, there are few studies regarding these markers in veterinary clinical oncology.Objectives: To determine the serum concentrations of cancer antigen 15.3 (CA 15.3), carcinoembryonic antigen (CEA), and lactate dehydrogenase (LDH) in female dogs with different stages of mammary cancer.Animals: Ninety female dogs, including 30 that were healthy, 40 that had nonmetastatic cancer, 12 with regional metastasis, and 8 with distant lymph node metastasis.Methods: Prospective case-controlled observational study. Serum samples were collected to measure CA15.3, CEA, and LDH from 60 female dogs with mammary cancer during mastectomy and 30 healthy female dogs during routine check-up. CA15.3 and CEA were determined by chemiluminescent immunoassay and LDH by ultraviolet kinetic method. Western blotting analysis was performed to confirm the specificity and possible cross-reactivity of human CA15.3 and CEA antibodies with canine serum. Group data were compared by ANOVA followed by Student-Newman-Keuls and Tukey's tests. Correlations were investigated by Pearson and Spearman tests.Results: CEA, CA15.3, and LDH were measurable in all groups. Higher serum concentration of CA15.3 and LDH was associated with regional and distant metastases. There was a significantly higher serum CA15.3 concentration in animals with lymph node metastasis when compared with animals without metastasis. There were no significant differences in CEA among groups. Expression of CA15.3 and CEA in canine serum was confirmed by Western blotting.Conclusions and Clinical Importance: Serum CA15.3 can be used to distinguish nonmetastatic from metastatic carcinomas.

The data suggest that inhibition of ovarian hormones and COX-2 may represent a therapeutic option for malignant feline mammary gland neoplasms. When evaluating disease progression, COX-2 scores and Ki-67 index should be analyzed in primary tumors and metastases. Histologic grade, HER-2 status and COX-2 scores were found to have a direct influence on OS. Prognostic factors allow for a better understanding of disease outcome in a condition that is characterized by a poor prognosis. The present work highlights the need for further studies on endocrine therapy and COX-2 inhibitors, which could influence OS.