Erythrocyte dysmorphism in canine and feline urinary sediment

The evaluation of urinary erythrocytes morphology by phase contrast microscopy has been proposed in human medicine to orientate the diagnosis towards a glomerular or a non glomerular disease. These aberrant shape erythrocytes appear when the physiological barrier of the glomerulus is disrupted. Acanthocytes or G1 cells are considered more specific for glomerular disease. The aim of this study was to detect the presence of dysmorphic erythocytes in feline and canine urine sample and their relation to the clinical status of the patient. Urine samples from privately owned 73 dogs and 35 cats were collected during their routine sanitary check-up. Urinalysis was performed according to the European Urinalysis Guidelines (2000) and the urine protein/creatinine ratio (UPC) was assessed. The resuspended sediment was observed by a phase contrast microscopy. Fifty urine samples were positive to dipstick for blood: in 11 sediments erythrocyte dysmorphism was evidenced (8 dogs and 3 cats). In these samples, the proteinuric pattern was investigated by SDS-page. Presence or absence of RBC dysmorphysm wasn’t statistically related to serum urea and creatinine, urinary chemical parameters, UPC, casts, lipiduria (free droplets or included in casts or cells). In 10 of these patients, signs of nephropathy were evidenced by an increase of serum creatinine and/or elevated UPC and/or anomalous proteinuric pattern in SDS-page and/or ultrasound evidences and/or histopathologic findings. These urine samples belonged to: six animals affected with CKD stage 1, two animals in CKD stage 2 and one in CKD stage 3. In one case, nephropathy was not objectifiable. This subject was affected with neoplasia that, despite being an extra-renal disease, puts the kidney at risk of immune-complexes precipitation in the glomerulus. In two urine samples belonging to normoazotemic patients with normal UPC, a consistent transferrinuria was detected by SDS-page. In humans with type 2 diabetes, transferrinuria is considered the earilest marker of glomerular injury because its less anionic and globular form. These two features make it more easily "ultrafilterable" by glomeruli, despite the higher than albumin molecular weight. In urine sediments dysmorphic erythrocytes, acantocytes and bizarre forms characterized by multiple blebs were observed. We underline that a non dysmorphic hematuria was detected in nine patients with evidence of CKD. In our preliminar observations: erythrocyte dysmorphism was concomitant with nephropathy in various stages and associated with signs considered early indicators of nephropathy in human medicine. Furthermore, dysmorphism was not identified in half of patients with renal disease.