Canine mammary tumors (CMTs) are a significant health issue in veterinary medicine, being among the most common carcinomas in female dogs. This review summarizes the classification, biomarkers, and treatment options for CMTs. CMTs are classified into benign and malignant forms, with malignant tumors being more common. The World Health Organization (WHO) and the Davis-Thompson DVM Foundation have established a classification system for CMTs, which includes 23 malignant and 7 benign subtypes. Malignant CMTs are often adenocarcinomas, carcinosarcomas, or solid carcinomas, while benign forms include ductal papillomas, fibroadenomas, and simple adenomas. Biomarkers such as estrogen receptor (ER), progesterone receptor (PR), and HER-2 are used for diagnosis and treatment. Traditional therapies for CMTs include surgery, chemotherapy, radiotherapy, and hormonal therapy. However, these treatments may not always be sufficient, and advancements in understanding cancer mechanisms and the development of personalized medicine offer hope for improved outcomes. Personalized medicine, which tailors treatment to individual patients, is gaining interest in both human and veterinary oncology. Immunotherapy is also being explored as a novel therapeutic option. Biomarkers such as Ki-67, p53, VEGF, and miRNAs are important for diagnosis, prognosis, and treatment. The treatment of CMTs includes surgery, radiotherapy, hormonal therapy, chemotherapy, targeted therapy, and virotherapy. Surgery remains the first choice for many CMTs, followed by other treatments. Hormonal therapy, such as the use of LHRH agonists and progesterone antagonists, may be effective in some cases. Chemotherapy is used in metastatic or inflammatory CMTs. COX-2 inhibitors are also being explored as potential therapies. Anti-angiogenic treatments, such as monoclonal antibodies, are being tested in veterinary medicine. Oncolytic viruses are also being studied as a new strategy for cancer treatment. Personalized medicine, or precision medicine, aims to tailor treatment to individual patients based on genetic, lifestyle, and environmental factors. This approach involves the use of genetic information to achieve optimal therapeutic care. The analysis of the tumor microenvironment (TME) is a critical aspect of precision medicine, as it includes not only the tumor cells but also various tumor-associated cells that influence tumor progression and treatment efficacy. The development of new molecular assays to measure specific mutations, genes, and proteins is important for diagnostics in this medical model. Overall, the treatment of CMTs is a complex process that requires a multidisciplinary approach, and the integration of personalized medicine is essential for improving outcomes in canine patients.Canine mammary tumors (CMTs) are a significant health issue in veterinary medicine, being among the most common carcinomas in female dogs. This review summarizes the classification, biomarkers, and treatment options for CMTs. CMTs are classified into benign and malignant forms, with malignant tumors being more common. The World Health Organization (WHO) and the Davis-Thompson DVM Foundation have established a classification system for CMTs, which includes 23 malignant and 7 benign subtypes. Malignant CMTs are often adenocarcinomas, carcinosarcomas, or solid carcinomas, while benign forms include ductal papillomas, fibroadenomas, and simple adenomas. Biomarkers such as estrogen receptor (ER), progesterone receptor (PR), and HER-2 are used for diagnosis and treatment. Traditional therapies for CMTs include surgery, chemotherapy, radiotherapy, and hormonal therapy. However, these treatments may not always be sufficient, and advancements in understanding cancer mechanisms and the development of personalized medicine offer hope for improved outcomes. Personalized medicine, which tailors treatment to individual patients, is gaining interest in both human and veterinary oncology. Immunotherapy is also being explored as a novel therapeutic option. Biomarkers such as Ki-67, p53, VEGF, and miRNAs are important for diagnosis, prognosis, and treatment. The treatment of CMTs includes surgery, radiotherapy, hormonal therapy, chemotherapy, targeted therapy, and virotherapy. Surgery remains the first choice for many CMTs, followed by other treatments. Hormonal therapy, such as the use of LHRH agonists and progesterone antagonists, may be effective in some cases. Chemotherapy is used in metastatic or inflammatory CMTs. COX-2 inhibitors are also being explored as potential therapies. Anti-angiogenic treatments, such as monoclonal antibodies, are being tested in veterinary medicine. Oncolytic viruses are also being studied as a new strategy for cancer treatment. Personalized medicine, or precision medicine, aims to tailor treatment to individual patients based on genetic, lifestyle, and environmental factors. This approach involves the use of genetic information to achieve optimal therapeutic care. The analysis of the tumor microenvironment (TME) is a critical aspect of precision medicine, as it includes not only the tumor cells but also various tumor-associated cells that influence tumor progression and treatment efficacy. The development of new molecular assays to measure specific mutations, genes, and proteins is important for diagnostics in this medical model. Overall, the treatment of CMTs is a complex process that requires a multidisciplinary approach, and the integration of personalized medicine is essential for improving outcomes in canine patients.