RESUMO
Canine visceral leishmaniasis frequently causes glomerulonephritis and tubulointerstitial nephritis, nephropathies for which diagnosis has been limited by the low sensitivity of traditional tests. The aim of this study was to evaluate serum cystatin C and urinary gamma-glutamyltransferase (uGGT) levels and the urinary GGT/urinary creatinine ratio (uGGT/uCR) and to measure the renal arterial resistive index (RARI) in dogs with leishmaniasis with varying degrees of renal injury based on the urine protein: creatinine ratio (UP/C) and serum creatinine (SCr) level. We tested 59 untreated adult dogs of both sexes and undefined breeds naturally infected with Leishmania infantum. The dogs were grouped into four groups based on UP/C and SCr level: group 1 (n = 15), dogs with SCr levels < 1.4 mg/dL and UP/C < 0.5; group 2 (n = 13), dogs with SCr levels < 1.4 mg/dL and UP/C of 0.5-1.0; group 3 (n = 16), dogs with SCr levels < 1.4 and UP/C > 1.0; and group 4 (n = 15), dogs with SCr levels > 1.4. A fifth group of healthy dogs (n = 10) was the control. uGGT concentrations and uGGT/uCR were higher in dogs with proteinuria and SCr < 1.4 mg/dL, whereas the serum cystatin C concentrations and RARI were higher only in dogs with SCr levels > 1.4. In conclusion, uGGT and uGGT/uCR may be useful tools for early detection and assessment of renal lesions associated with leishmaniasis; however, cystatin C is useful for monitoring the progression of kidney disease when measured sequentially.