Portal vein hypoplasia (PVH) is a congenital disorder, in which microscopic intrahepatic shunts are present, causing blood to bypass the liver sinusoids. As the clinical presentation and the laboratory findings are similar to those in dogs with an extrahepatic portosystemic shunt (EHPSS), differentiation between both disorders is based on the confirmation of a macroscopic shunt by diagnostic imaging techniques. This review highlights the major aspects of PVH, including the differentiation from EHPSSs, and the challenges to diagnose both disorders in dogs with concurrent PVH and EHPSS
