Taking into account the oncogenic role of the SDF-1/CXCR4 axis in human breast cancer and the promising data on its inhibition, we aimed to determine if the serum SDF-1 levels have diagnostic value in cats with mammary carcinoma and to calculate the best cut-off value, which allows to discriminate between sick and healthy animals. The gene discussed is CXCR4; the disease is breast carcinoma.