Introduction: Apocrine sweat gland carcinomas (ASGCs) are malignant neoplasms of dogs and other animals, rarely reported worldwide. The aim of this study was to summarise the occurrence of this cancer in a population of dogs in Poland between 2009 and 2014 with regards to histological features and body location of the tumours, as well as age, sex and breed of the cancer-affected dogs.Material and Methods: The study involved 40 canine ASGC cases diagnosed in five national veterinary pathology laboratories. The material was processed according to routine histological methods.Results: Histological types of the tumours involved simple and complex apocrine carcinoma of cystic/papillary (62.5%), solid (15%), and tubular type (12.5%), as well as apocrine ductal carcinoma (10%). The epidemiological analysis revealed peak incidence of the cancer in dogs between 8 and 14 years of age, with the most commonly affected sites being forelimbs and thorax. The highest number of the cancer cases was diagnosed in mixed breed dogs and German Shepherds; no sex predilection was noted.Conclusion: To the authors’ knowledge, this is the first report recounting the study on canine malignant apocrine sweat gland tumours in Poland providing detailed phenotypical and histological data, which are otherwise rarely described in veterinary literature. This type of cancer appears to be diagnosed more frequently in dogs than in humans. Being an easily accessible material for research, canine ASGCs might serve as a relevant animal model for studies related to pathogenesis of sweat gland tumours.

Triple-negative breast cancer is a type of breast cancer that does not express the genes for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER-2). It is an important and clinically relevant condition as it has a poor prognosis and is difficult to treat. Basal-like triple-negative cancer is highly prevalent in both African-Americans and adolescents. We therefore examined whether such a cancer likewise occurs in specific breeds and age groups in dogs, focusing on basal-like triple-negative cancer in particular. In this study, 181 samples from dogs with malignant mammary carcinoma from the 5 most common breeds and 2 age groups in Korea were analyzed. Histological classification and molecular subtyping, including assessment of immunohistochemical findings, were carried out. Twenty-five of 28 (89.3%) triple-negative carcinomas were identified as basal-like triple-negative carcinomas. Analysis of associations of classified factors revealed that the shih tzu breed (9/25, 36.0%) and advanced-age (19/25, 76.0%) groups were characterized by higher prevalence of basal-like triple-negative tumors with diverse histological types and of a higher grade. These results suggest that breed- and age-related differences can be identified in canine mammary carcinoma and, notably, in the shih tzu breed and at older ages. Further investigation of these distinguishing characteristics of the shih tzu breed is warranted.

Breast tumors are the most common tumors in dogs and the study of disease prognostic factors is important for establishing the appropriate treatment protocols. The purpose of this study was to clinically stage mammary tumors of bitches and correlate the stages with histological type and grade. The tumors of 63 dogs were clinically staged based on the findings of tumor sizing, lymph node evaluation, and radiographic examination. After surgical excision, the tumors were classified histologically and graded. The relationship between the tumor grade, stage, and histological type was evaluated using a binomial test. Stage I tumors were the most numerous (31.75%), followed by tumors at stages II, III, IV, and V. Animals with histological grade I carcinomas presented stage I, II, or III tumors more frequently and stage IV and V tumors less frequently. The number of animals with simple carcinomas that were at stage I of the disease was greater than that at stage V. Carcinomas in the mixed tumors were less aggressive; however, the small number of animals in stage V of the disease made any statistical association impossible. The complex carcinomas presented with the invasion of the lymph nodes and less cellular differentiation in a larger number of animals than did simple carcinomas. Histological grading proved to be the best parameter for the prognostic evaluation of the breast carcinomas.