This study evaluates distal tubular damage in early stages of renal disease in dogs with naturally acquired Leishmaniosis.Pherograms of urinary proteins separated in vertical electrophoresis system (SDS-PAGE) were evaluated. Peptide fingerprint and fragmentation (MALDI-TOF TOF) identified bands located at 100 and 60kDa as Tamm-Horsfall protein (THP) and albumin respectively.The variables examined were: urine protein to creatinine ratio (UPC), total number of bands, quantification of THP urinary excretion through the optical density of bands located at 100kDa, blood creatinine and urine specific gravity (USG).Positive correlation was found between UPC and the number of bands (ρ = 0.75849, P = <0.0001). Negative correlation was identified between UPC and OD % (optical density percentage) of 100kDa bands (ρ = -0.85332, P = <0.0001), and the number of bands and OD % of 100kDa bands (ρ = -0.74479, P = <0.0001).The area under the ROC curve was 0.991 (95% CI, 0.976 to 1). The optimal cut-off UPC that better discriminated between urines with high or low OD% of THP was 0.46 with 92.6% sensitivity and 96.2% specificity.Our findings indicate that non azotemic dogs with borderline proteinuria might excrete low concentrations of THP which could suggest tubular damage in early stages of chronic kidney disease.