This study evaluated the utility of new renal biomarkers in canine leishmaniosis (CanL). A total of 6 healthy dogs (CG) and 22 dogs with CanL (LeishVet stage III or GIII (n = 11) and stage IV or GIV (n = 11)) were included. Plasma creatinine, urea, cystatin C (pCysC), and symmetric dimethylarginine were analyzed. In urine, neutrophil gelatinase-associated lipocalin, retinol-binding protein, Tamm-Horsfall protein, and total protein were measured using their ratios with creatinine (uNGAL/c, uRBP/c, uTHP/c, and UPC, respectively). The estimated glomerular filtration rate (eGFR) was assessed by 99mTc-DTPA scintigraphy. All glomerular biomarkers strongly correlated with eGFR and showed statistically significant differences between CanL stages but not with CG, except for pCysC, which was particularly noteworthy for its statistical significance, instilling confidence in its potential use. All tubular biomarkers presented significant differences between GIV and CG
however, only uNGAL/c and uTHP/c differentiated between GIII and CG. Moreover, none could distinguish between the GIII and GIV groups. These data suggest that the new glomerular biomarkers could help determine stages of renal disease in CanL. uNGAL/c and uTHP/C showed advantages in making an earlier diagnosis. Ultimately, pCysC presented tremendous potential, as it was statistically significant for both uses. This research provides valuable information to understand the behavior of these biomarkers in renal disease secondary to CanL.