In CKD dogs with stage 3, during the follow-up, only two dogs changed the classification to stage 4 based on serum creatinine concentrations, however when taking SDMA concentrations (> 45 μg/dL), 9 out of 12 changed the classification to stage 4 and among them, 6 out 9 dogs that had serum creatinine < 5.0 mg/dL were already in stage 4 since the beginning of the follow-up.