Occurrence and oncopathological characterization of canine epithelial tumors with special reference to mammary neoplasms

Abstract

The present study was conducted at the Department of Veterinary Pathology, Veterinary College, Shivamogga, to document the prevalence, classification, and characterization of canine epithelial tumors, with emphasis on mammary gland tumors. A five-year retrospective analysis (2019-2024) of 8,671 canine cases revealed the occurrence of tumors in 268 dogs (3.09%) dogs, with non-descript dogs showing the highest frequency (30.22%) of occurrence. Middle-aged to older dogs (5-13 years) and females (67.6%) were more predisposed. During a one-year prospective study on canine tumors (July 2024-June 2025), 67 tumor cases were recorded and analyzed. Mammary tumors were the most frequent epithelial tumors (17/25), affecting Pomeranians, Labradors, Dobermanns, and Golden Retrievers. Grossly, tumors exhibited nodular, lobulated, cystic, or ulcerated masses. Cytology and histopathology differentiated malignant from benign based on pleomorphism, mitotic activity, stromal invasion, and desmoplasia. Predominantly malignant (13/17) and few benign (4/17) mammary tumors were recorded, including invasive ductal carcinoma, mixed mammary tumor, invasive ductal adenocarcinoma, and mammary squamous cell carcinoma, while other epithelial tumors included squamous cell carcinoma, oral papilloma, and ovarian adenocarcinoma. PCR and sequencing of p53 revealed point mutations in four malignant tumors, but not in benign tumors, indicating its role in malignancy.