Portal vein thrombosis is being recognized with increased frequency in small animals due to greater awareness of hypercoagulable states and greater use of abdominal ultrasound in animals with gastrointestinal signs. The veins of the hepatic portal system drain the digestive organs, spleen and pancreas and deliver blood to the liver via the hepatic portal vein. The portal vein is responsible for delivering close to 75 percent of the hepatic blood supply, the remaining being provided by hepatic arteries. Obstruction of the portal vein occurs most commonly secondary to thrombus formation, or due to neoplastic infiltration and secondary thrombus formation.
Clinical investigation of hemostasis in dogs and cats with naturally-occurring disease processes is facilitated by the state-of-the-art equipment housed in the coagulation laboratory at the Foster Hospital for Small Animals at Tufts University. A recent study performed at Tufts (JAVMA: Fenty et al.) used thromboelastography to document hypercoagulability in dogs with immune-mediated hemolytic anemia prior to therapy with prednisone. Certainly this population of dogs is known to experience severe thrombotic complications, at times despite aggressive anticoagulation.