Öz
In bitches, the incidence of mammary tumors is determined at %50 of all neoplasms. Most of the cases are malignant and tend to metastasize. Because of this, early diagnosis has an important value. Due to the molecular and clinical similarities of canine mammary tumors to human breast cancers, human breast cancer markers are also detectable in cases of canine mammary tumors. Generally, biomarkers provide information about criteria such as clinical diagnosis, early diagnosis, prognosis, and determination of the treatment protocol. When choosing the appropriate biomarker, it should be taken into account that it is easy to apply, has a positive correlation with tumor specificity and malignancy, and whether gives precise information about prognosis. Due to the heterogeneous nature of canine mammary tumors, an ideal biomarker has not determined yet. However, new studies have revealed the existence of many biomarkers. In this review it is given to qualified and current biomarkers can be used in dogs, including invasive and non-invasive mammary tumor biomarkers.