KL and chronic kidney disease: Therefore, the aim of this study was to identify the characteristics of soluble alpha-klotho in CKD dogs by measuring serum and urinary alpha-klotho levels and verify their association with IRIS CKD stages and other parameters, including serum SDMA (sSDMA), creatinine, blood urea nitrogen (BUN), and phosphorus concentrations, which are known to be associated with CKD.