SDS-PAGE Electrophoresis for Urinary Protein Analysis in Dogs with Chronic Kidney Disease and Urinary Tract Infection

The objective of the present study Was to investigate urinary protein profiles in dogs with chronic kidney disease (CKD) in comparison to dogs with urinary tract infection (UTI). Animals were divided into 4 groups: control, CKD stages II+III, stage IV and UTI. Blood pressure was measured using oscillometric method. Blood was collected for determinations of packed cell volume (PCV), blood urea nitrogen (BUN) and plasma creatinine concentrations. Urine was collected for urinalysis and protein determination. Total urinary proteins were measured using semi-quantitative method by precipitation with sulfosalicylic acid and a standard SDS-polyacrylamide gel electrophoresis (SDS-PAGE) which were presented as urinary protein creatinine (UPC) ratio and electrophoresis urinary total protein creatinine (E-UTPC) ratio, respectively. The protein of high molecular weight (HMW) (> 67 kDa), middle molecular weight (MMW) (66-67 kDa) and low molecular weight (LMW) (<66 kDa) were determined. The results showed that blood pressure in dogs with CKD stage IV was significantly higher than the control healthy group (p < 0.05). The PCV was lower in dogs with CKD stage IV compared with the control and UTI group (p < 0.05). Dogs with CKD stage II+III or IV had significantly higher UPC ratio and E-UTPC ratio (p < 0.05) compared with the control group. Although dogs with UTI had higher E-UTPC ratio compared with the control group, it was lower than dogs with CKD stage IV (p < 0.05). There were positive correlations between plasma creatinine concentration and both proteinuria (HHW; p < 0.01 and MMW; p < 0.05) and mean arterial blood pressure (p < 0.05). The urinary protein distributions in CKD groups were similar to UTI. It is concluded that although the proteinuria in CKD was higher than UTI, the degree and pattern of urinary protein with different molecular weight could not be used to distinguish between CKD and UTI in dogs.