NEPHROTIC RANGE PROTEINURIA AND ALBUMINURIA IN DOGS: A RETROSPECTIVE EVALUATION OF 338 CASES

In dogs, persistent renal proteinuria with Urinary Protein to Creatinine ratio (UPC) ≥2.0 usually is due to glomerular renal disease. In humans, Nephrotic-Range Proteinuria (NRP) is defined as UPC ≥ 3.5, while Overt Albuminuria (OA) is defined as Urinary Albumin to Creatinine ratio (UAC) > 0.3. Analogous cut-off values are lacking for dogs. The aim of this study was to characterize clinical and clinicopathological features associated with 'glomerular proteinuria' in dogs, with particular regard to UAC.Retrospective analysis included a total of 338 dogs admitted to our Teaching Hospital, between January 2002 and September 2011, with glomerular proteinuria defined by UPC ≥2.0. Data collected were signalment, clinical and clinicopathological findings including Blood Pressure, CBC, serum Albumin (Alb), Total Protein, Cholesterol, Creatinine (Crea), Urea, Electrolytes, CRP, Total Iron, Total Iron Binding Capacity (TIBC), Antithrombin%, D-Dimers, Fibrinogen, and urinalysis comprehensive of UPC and UAC (immunoturbidimetric method). Data were analyzed with descriptive and non parametric statistics. A difference was considered significant for p <0.05. The number of dogs included in the statistical analyses was not uniform because some results were not available for all dogs.Median age was 8.4 years (range 0.25-17.4) with a 58.8% of male and 32.5% of mixed-breed. An underlying inflammatory disease was recognized in 61% of dogs (24.2% Leishmaniasis). The Median UPC was 4.9 (range 2.0-40.1) and according to the human cut-off (UPC ≥3.5) 65% of dogs was classified as having NRP. UAC was available in 309/388 patients (Median 2.24; range 0.001-25.391; RI <0.024) and 92% of dogs (287/309) presented OA (UAC >0.3). Hypoalbuminemia (Alb ≤2.5 g/dl) was detected in 57.2% of cases (Median 2.35; range 0.74-4.29). A significant negative correlation between UPC, UAC and Alb (r=-0.43 and r=-0.25, respectively), was detected. Crea concentration was above the reference interval in 53% of dogs (Median 1.85; range 0.47-22.07; RI 0.65- 1.35). Median Fibrinogen concentration was 5.28 g/l (range 0.64-10.63; RI 1.45-3.85), Median D-Dimers concentration was 0.26 μg/ml (range 0.01-8.84; RI <0.26). Median CRP concentration was 3.22 mg/dl (range 0.01-40.38; RI <0.5) and 76% of dogs presented elevated CRP. NRP dogs showed a significant increase in CRP, Phosphorus, Urea and D-Dimers and a significant decrease in Alb, HCT and TIBC.These findings suggest that NRP dogs have higher inflammatory state and potential hemostatic imbalance on clinical pathology. Further studies are required to investigate the potential role of UAC in the diagnosis of protein-losing glomerulopathies in dogs.