Abstract
Cancer is a complex pathological condition associated with substantial rates of mortality and morbidity in both humans and animals. Mammary gland tumors in intact female dogs are the most prevalent neoplasms. Surgical intervention remains the primary treatment choice. Alternative therapeutic options have emerged, with histopathological examination being fundamental to confirm the diagnosis and to decide the best therapy. This research focused on the clinicopathological, immunohistochemical, and cytogenetic aspects of canine mammary tumors (CMTs). Most of the animals were mixed-breed, with the majority being older than seven years, and only 16.7% had been spayed before surgery. Caudal abdominal and inguinal mammary glands were the most affected, with regional mastectomy being the predominant treatment (75.0%). Of all the tumors, 29.1% were benign, while 70.9% were malignant. Complex adenoma was the most common benign tumor, whereas tubulopapillary carcinoma was the most common malignant type. Grade III tumors (17.6%) were the least encountered, while grades I and II exhibited a similar prevalence (41.2%). All the carcinomas were classified as luminal, and cytogenetics analysis demonstrated a high chromosomal instability with significant aneuploidy observed in all cases and polyploidy detected in 62.5%. This study holds significance as canine and human breast cancers share similar characteristics, suggesting that dogs could be a valuable model for human breast cancer research. Further studies with larger sample sizes are needed to enhance our understanding of CMTs.