veterinary UnicPet nefrology and urology in dogs and cats São Paulo, Sao Paulo, Brazil
Abstract: In dogs, glomerular proteinuria may result from systemic hypertension, glomerular hyperfiltration, or glomerulonephritis—conditions typically managed with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. However, the urinary protein-to-creatinine ratio (UPC), widely used in clinical settings, cannot differentiate the origin of renal proteinuria (RP)—whether glomerular, tubular, or mixed. SDS-PAGE urinary protein electrophoresis has emerged as a promising tool to qualitatively identify the predominant origin of RP by distinguishing glomerular (GEP), tubular (TEP), or mixed (MEP) electrophoretic patterns, potentially supporting more appropriate therapeutic decisions. This study aimed to demonstrate that relying solely on UPC may result in suboptimal treatment of RP. Twenty-five dogs with renal proteinuria and chronic kidney disease (CKD), stages 1 to 4 (11 males, 14 females; mean age 9.8 ± 2.9 years; various breeds), were evaluated. UPC values were compared to SDS-PAGE electrophoretic patterns. MEP was the most frequently observed pattern (68.0%, n=17), with a mean UPC of 8.8 ± 8.4. TEP and GEP were each observed in four dogs (16.0%), with mean UPCs of 6.7 ± 3.5 and 4.3 ± 3.2, respectively. In GEP cases, the predominant protein band was observed between 60–70 kDa, likely representing albumin. Importantly, no bands were detected between 90–100 kDa, which could correspond to Tamm-Horsfall protein. These findings suggest that MEP can be predominant in dogs with RP. Therefore, a more accurate identification of RP origin may require both quantitative (UPC) and qualitative (SDS-PAGE) assessments. This combined approach could enhance the localization of nephron damage and guide more effective treatment strategies in dogs with renal proteinuria.
