Abstract

Canine mammary tumours (CMTs) are the most common neoplasms in intact female dogs and are of considerable interest in veterinary oncology due to their clinical significance and translational relevance to human breast cancer. This study investigated the epidemiologicaldeterminants and histopathological spectrum of CMTs in central Kerala, to identify risk factors and characterise tumour biology in a regional context. Fifty cases (48 biopsies and 2 necropsies) comprising 66 tumour masses were collected from the University Veterinary Hospitals at Mannuthy and Kokkalai and the Department of Veterinary Pathology, Mannuthy, between May 2024 and August 2025. Clinical variables including age, breed, sex, reproductive status, diet, body condition and glandular involvement were analysed. Histopathological classification and grading were performed on haematoxylin and eosin–stained sections following Goldschmidt et al. (2011) and Elston and Ellis (1991) criteria. The mean age of affected dogs was 8.94 ± 0.41 years, with peak incidence between 10 and 12 years. Labradors (36%), crossbreeds (22%) and German Shepherds (14%) were most affected. Females accounted for 96% of cases, with nulliparous animals forming the majority (56%). The inguinal glands were most frequently involved (58%), followed by caudal abdominal glands. All tumours were malignant, with carcinosarcoma (15.1%), carcinoma mixed type (10.6%) and solid carcinoma (10.6%) predominating. Histological grading revealed Grade II tumours as most common (56.1%), followed by Grade III (27.3%) and Grade I (16.7%). The predominance of aggressive histological subtypes and higher-grade tumours highlights the malignant profile of CMTs in this region and underscores their value as a comparative model for human breast cancer research.

Keywords : Canine mammary tumours, epidemiology, histopathology, carcinosar coma, risk factors