Vol. 9, Issue 10, Part J (2025)

The present study examined 50 spontaneous canine mammary tumors to assess their distribution based on age, breed, and glandular involvement, along with their gross, cytological, and histopathological features. Mammary tumors were most frequently observed in middle-aged female dogs, with a mean age of eight years and a peak incidence between six and eight years. Labrador Retrievers were the most commonly affected breed, followed by non-descriptive breeds, Golden Retrievers, and Dachshunds. All affected dogs were females, predominantly intact, indicating a strong hormonal influence in tumor development. The caudal abdominal and inguinal glands, especially on the left mammary chain, were the most frequently involved sites. Grossly, the tumors varied from well-circumscribed solitary nodules to large, multifocal, ulcerated, or cystic masses. Malignant tumors accounted for 70% of the total cases, while benign and hyperplastic lesions comprised the remainder. Cytological evaluation of malignant tumors revealed high cellularity, marked pleomorphism, and a high nuclear-to-cytoplasmic ratio, whereas benign tumors exhibited cellular uniformity and low mitotic activity. Histopathologically, tubular carcinoma was the most prevalent malignant subtype, followed by complex and cystic papillary carcinomas, while simple adenomas were the most common benign lesions. The observed histological patterns were consistent with established classifications of canine mammary neoplasia, validating the use of cytology as a reliable diagnostic tool. Overall, the findings emphasize that spontaneous mammary tumors are common in intact, middle-aged female dogs, with the caudal mammary glands being the most affected sites, highlighting the importance of early cytological screening and histopathological evaluation for accurate diagnosis and management of canine mammary neoplasia.