Kidney diseases commonly affect dogs and cats. Early diagnosis of renal impairment may be challenging even when urinalysis is used to provide additional information. Serum creatinine concentration is often used in the diagnosis, but it is a relatively insensitive marker of renal function. Particular attention is aimed at the investigation of certain molecules that may occur in urine at elevated levels as a result of glomerular or tubular dysfunction. These changes may be found before the increase of serum creatinine levels. This review article summarises reports of urine biomarkers and their utility in detecting early kidney disease in dogs and cats. Detection of multiple urinary biomarkers in diagnosis of acute kidney injury and chronic kidney disease may increase specificity and sensitivity. Early diagnosis of reduced renal functional mass allows early therapeutic interventions which may decrease morbidity and mortality.
Keywords: microalbuminuria; neutrophil gelatinase-associated lipocalin; N-acetyl-β-d-glucosaminidase; gammaglutamyl transpeptidase; immunoglobulin GAbbreviations AKI = acute kidney injury; ARF = acute renal failure; CKD = chronic kidney disease; CRP = C-reactive protein; GFR = glomerular filtration rate; GGT = gamma-glutamyl transpeptidase; HMW = high molecular weight; ICU = intensive care unit; IgG = immunoglobulin G; NAG = N-acetyl-β-d-glucosaminidase; NGAL = neutrophil gelatinaseassociated lipocalin; PTH = parathormone; RBP = retinol binding protein; UAC = urinary albumin to creatinine ratio; uGGT = urinary gamma-glutamyl transpeptidase; uNAG = urinary N-acetyl-β-d-glucosaminidase; UNCR = urinary neutrophil gelatinase-associated lipocalin to creatinine ratio; UPC = urinary protein to creatinine ratio; uRBP = urinary retinol binding protein; UTI = urinary tract infection