Hepatorenal syndrome (HRS) is a unique form of functional and potentially reversible renal failure secondary to liver diseases. It occurs typically in kidneys that are histologically normal. In this study, the hepatorenal syndrome was observed in a model of extrahepatic biliary stasis. Seven mature male mongrel dogs were subjected to complete surgical ligation of common bile duct at the duodenal region Clinical, ultrasonographic, , histopathological examinations along with biochemical analysis for liver enzymes and urinalysis were performed before and throughout the experimental periods. Clinical observations post-surgery revealed icteric mucosa, abdominal pain, weight loss, dehydration, orange-colored urine, bilirubinurea, and clay feces. Biochemical analysis showed an abrupt increase in the mean values of serum blood urea nitrogen and creatinine from the 3 rd day till reaching the peak at the 2 nd week post-surgery. A strong positive correlation was detected between BUN and creatinine, and serum total and direct bilirubin. Ultrasonographic findings of liver revealed a progressive dilatation of gallbladder and the common bile duct from the 3 rd day post-ligation, with an increase in the echogenicty of the liver, whereas, the kidneys demonstrate normal renal parenchyma and dimensions. Histopathological examination of the kidney revealed hemorrhage, vacuolation, hyaline droplet were observed in renal tubules and edema and yellowish-brown granules were seen in the interstitial tissue, but the significant renal changes that refer to renal failure weren't detected,. In conclusion, the dogs are considered a suitable model for studying hepatorenal syndrome and also there is an association between obstructive jaundice and renal failure.

To explore the role of ultrasound in the diagnosis of extrahepatic cholestasis in dogs, an experimental extrahepatic cholestasis was done successfully in seven male mongrel dogs via common bile duct ligation that mimic natural cases in dogs. All observations and changes were recorded post-operative; clinical, biochemical and ultrasonography. All dogs showed jaundice, orange colored urine and clay feces in the 3 rd day post-operative. Significant increase in serum levels of AST, ALT, GGT, ALP, total and direct bilirubin post-operative started from the 3 rd day till reaching the peak in the 2 nd week, then declined again from the 3 rd week post-surgery till reaching the lowest level at the 8 th week. Meanwhile, there was a significant decrease in both total protein and albumin started from the 3 rd day post-ligation and remained till the end of the study. Ultrasonography of biliary system showed significant dilatation of gallbladder and common bile duct starting from the 3 rd day post-ligation till reaching the maximum in the 2 nd week that showed a slight reduction in their diameter from the 3 rd week and reached the lowest diameter in the 8 th week post-ligation. Post mortem examination showed jaundice, emaciation, as well as gallbladder and common and cystic duct dilatation. Histopathology of liver showed subcapsular hemorrhage, congestion of central vein with vacuolation in hepatocytes and yellowish brown granules of bile pigment inside other hepatocytes. In conclusion, the usage of biochemical analysis and ultrasonography is very important in early diagnosis of extrahepatic cholestasis as the changes appeared within 3 days after obstruction.