The present invention relates to a method and device for creating and testing arterial and venous thrombotic conditions. The invention includes a tube which is inserted into a blood vessel of an animal. The tube contains one or more strands upon which various materials, such as procoagulants and anticoagulants may be placed. Blood flows through the tube and clots form on the threads. After the completion of the test, the tube is removed from the animal, the strands are removed from the tube and the clots may be measured and weighed. In a preferred embodiment, a flowmeter may be connected to the blood vessel to measure the blood flow so that the clot measurements may be correlated with the blood flow.