The importance of urinary enzyme activities in dogs with experimentally induced gentamicin nephrotoxicity

Totally nine healthy and mature dogs were used in the study. Two of which were served as controls and remaining seven dogs were assigned to experimental group. Gentamicin sulphate was given to induce nephrotoxicity at the dose of 10 mg/kg body weight every 8 hours for 10 consecutive days. The samples of blood and urine were taken twice before the experiment and every other day during gentamicin infection and for 5 days after gentamicin injection was ceased. N-acetyl-beta-D-glocosaminidase (NAG), gamma-glutamyl transterase (GGT) and Alkaline phosphatase (ALP) and creatinine (CR), total protein (TP), glucose (GLU) and electrolyte (Ca, P, Na, K) concentrations in the urine samples and blood urea nitrogen (BUN), total protein (TP), albumin (ALB), cretainine (SCR), glucose and electrolytes (Ca, P, Na, K) concentrations in the blood samples were measured. Urine dip stick and microscopic examination of urine sediment were performed. Urine protein/creatinine rate and daily protein loss in urine were calculated. The fractionel clearances of electrolytes (Ca, P, Na, K) and glucose were determined. Sodium sulphanilate clearence was measured twice before the experiment and three times during the experiment. Daily clinical examination of all dogs were performed during the experiment. Autopsy and histopatologic examinations were performed in three dogs (1 control, 2 experimental group) on the 11th day of the experiment, two dogs were euthenasied due to uremic coma on the 12th day of the experiment and remaining dogs were necropsied at the end of the experiment. In this study, acute tubular necrosis induced with nephrotoxic doses of gentamicin was found to be occured between 7th and 10th days of the experiment on the basis of clinical and laboratory findings. Urine GGT activities were found to be increased (P<0.01) on the 7th day of the experiment, urine NAG and ALP activities did not significantly increase. Significant increaments in the GGT/CR (P<0.01) and NAG/CR (P<0.01), ALP/CR (P<0.05) rates were observed respectively on the 7(th) and 13(th) days of the experiment. In conclusion, GGT/CR rate was found to be the most sensitive and reliable indicator in the determination of renal tubular damage associated with gentamicin nephrotoxicity.