Ultrasound-guided renal biopsy is an essential diagnostics method which, by facilitating histopathological examination, can increase the accuracy of the differential diagnosis between acute and chronic nephropathies and will help the clinician perform an etiologic diagnosis, issue a prognosis and orient the therapy of the majority of parenchymal nephropathies. Due to the relative invasiveness and potential adverse effects, the use of renal biopsy is limited among practitioners. In this study we evaluate the intensity of renal damage induced by renal cortex sampling and the clinical consequences of such a procedure. We examined 28 dogs, mixed breed and variable ages, 11 (39, 29%) males and 17 (60, 71%) females that were referred to our clinic and underwent ultrasound-guided renal biopsy in order to establish a definite diagnosis. Patients were presented with a variety of diffuse nephropathies: kidney lymphoma: 1 (3.57%), glomerulonephritis: 13 (46.43%), tubulointerstitial nephritis: 11 (39.29%) and nephrocalcinosis: 3 (10.71%) of which 18 (64.29%) were in acute kidney failure and 10 (35.71%) were chronic renal patients. The type and the severity of renal lesions were correlated with changes in urinary NAG index (iNAG), and specific serum renal damage markers such as urea, creatinine, phosphorus and ionized calcium. To quantify the side effects of percutaneous renal biopsy, the magnitude of post biopsy haematuria and changes in urinary iNAG activity were evaluated. The results indicate a significant post biopsy increase in urinary iNAG activity in all patients that underwent this procedure (100.08±34.45 [U/g] pre-biopsy iNAG vs. 147.65±33.26 [U/g] post-biopsy iNAG, p<0.001) suggesting an intensification in renal tubular damage consecutive to kidney puncture and sampling.

Transitory macro- or microhaematuria was a constant finding in all dogs that underwent ultrasound-guided renal biopsy, but the magnitude and extent could not be associated with PLT (10⁹/L), aPTT (s) and PT (s) levels in our patients, and resolved after 12–24 hours without therapeutical interventions.

Percutaneous ultrasound-guided renal biopsy is a relatively safe, minimally invasive diagnostic procedure which will induce a series of deleterious effects on kidney structure and function, but we consider that a correctly obtained tissue sample with a high diagnostic value is of greater importance than the complications associated with the sampling procedure.

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