<p>Optimal cancer treatment requires thorough understanding of the biological behavior of the particular cancer affecting the patient and the extent of disease, i.e. the cancer stage. This typically necessitates a biopsy and a series of diagnostic tests and imaging. The trends in veterinary oncology have shifted towards more extensive presurgical staging tests with the availability of more sensitive diagnostic and imaging methods. This shift is also in part driven by a fear of missing metastatic lesions resulting in flawed treatment decisions. Thus, new staging recommendations are emerging and getting established without a critical review of their clinical indications and utility. Patients may undergo unnecessary diagnostics as new standards are established. Here we provide a review of the current staging practices in canine mammary tumors, and propose both a simplified and practical, but also evidence-based method for the presurgical and the immediate post-surgical staging approach in dogs with mammary tumors.</p>