SPX and chronic kidney disease: The aim of this study was to evaluate SPX concentration in serum from dogs and cats with chronic kidney disease (CKD) and to investigate the potential role of SPX in kidney cell metabolism using an in vitro model based on MDCK and CRFK cells.<h4>Results</h4>Our findings showed a significant reduction in serum SPX levels in animals with CKD (p < 0.01).