Antithrombotic Effect of Malayan Pit Viper Venom on Experimental Thrombosis of the Inferior Vena Cava Produced by a New Method

A reliable method of producing tlirombosis of the inferior vena cava in dogs is described. This consists of placing a segment of umbilical tape across the lumen of the vein and sewing it in place without interfering with blood flow. In the control animals gross thrombi were not usually present in the immediate postoperative period but were demonstrated after 24 hours. By the 7th postoperative day large red clots completely obstructing the vessel were usually found. The venom of the Malayan pit viper proved to be highly effective in preventing experimental thrombosis. The antithrombotic effect of viper venom is believed to be due primarily to induced hypofibrino-genemia. Accelerated fibrinolysis may also be a factor. The experiments sug-gest that Malayan pit viper venom may be effective as an antithrombotic agent. ADDITIONAL KEY WORDS anticoagulant snake venom hypofibrinogenemia fibrinolysis hemorrhagic complications Ancistrodon rhodostoma thrombocytopenia defibrinatio