Insertion site of congenital extrahepatic portosystemic shunts influences clinicopathological findings in dogs

Determine the influence of insertion site of extrahepatic portosystemic shunts (EHPSS) on clinicopathological findings in dogs. A retrospective study was performed in dogs diagnosed with an EHPSS. Cases were eligible if EHPSS morphology was categorized as portoazygos (PA) shunts, portocaval (PC) shunts entering the prehepatic caudal vena cava at the level of the omental foramen, or portophrenic (PP) shunts. Furthermore, completed standardized questionnaires on clinical signs at diagnosis had to be available. Signalment, clinical scores, and findings on blood analyses and medical imaging were determined and statistically analyzed. Data of 104 dogs (15 PA, 70 PC, and 19 PP shunts) were included. Dogs with PC shunts were significantly younger than dogs with PA and PP shunts. Furthermore, dogs with PC shunts had a significantly lower body condition score and a significantly worse clinical score compared to dogs with PP shunts. Microcytosis and monocytosis were more pronounced in dogs with PC shunts compared to those with PP shunts. Finally, urea and creatinine concentrations were significantly lower and preprandial serum bile acids and fasted ammonia concentrations were significantly higher in dogs with PC shunts than in those with PP shunts. Dogs with PC shunts are more likely to be presented at an earlier age, with more severe clinical signs and more distinct abnormalities in blood parameters compared to dogs with PP shunts. In older dogs with less distinct clinical signs suspected of having an EHPSS, screening for a PP shunt, which is more difficult to diagnose with ultrasonography, is recommended.