Two dogs were admitted with a history of anorexia, ataxia, shivering, lethargy, hypersalivation and seizure. Patients were suspected for portosystemic shunts on the basis of clinical signs, increased hepatic serum profiles on the blood test, microhepatica on plain abdominal radiographs, and an abnormally dilated and tortuous vessel on abdominal ultrasonographs. To diagnose PSS and to further evaluate type, shape, and location of shunt and hepatic vasculatures, the computed tomography (CT) angiography for portal and systemic circulation was performed. The shape, location and pathway of extrahepatic single shunt were confirmed in two dogs. Dual phases (the arterial phase and the venous phase) CT angiography and reformatted and three-dimensional images offered good understanding of PSS and planning surgical treatment.