A nine months old mix breed dog was presented by lethargy, symptoms of abdominal pain, mild respiratory distress and abrupt onset of massive and hemorrhagic ascitesthat responded to medical treatments partially. The dog had a history of car accidentthree months earlier. Mild non-regenerative microcytic anemia,hypoalbuminemia, hypoproteinemia, elevated liver enzymes, mild pulmonary edema and high protein transudate in abdominal cavity weredetected. Abdominal ultrasonography demonstrated hepatomegaly and intra-abdominal fluid collection. Histopathological examination of the liver biopsy showed a diffuse sinusoidal distension with some area of hepatocyte necrosis. The histopathological findings, together with increased level of liver enzymes, and moderate panhypoproteinemia, high protein transudate and abdominal pain were all in favorof the diagnosis of post-sinusoidal hypertension secondary to obstruction of hepatic venous outflow (Budd-Chiari-like syndrome). CT angiography confirmed a massive thrombosis in caudal vena cava and pulmonary artery. Unfortunately, 24 hours after CT scan study the patient was spontaneously expired. However, because the owner did not give his consent for the autopsy, the detailed data is not acquired. In conclusion, obstruction of venous blood flow and Budd-Chiari like syndrome must be considered in dogs with ascites, hepatomegaly, and symptoms abdominal pain.