A model of venous thrombosis induced by stasis and Feiba in rabbits

A model of venous thrombosis, induced by injection of Feiba(R) (Factor Eighth Inhibitor Bypassing Activity) plus stasis, was studied in the jugular veins of anaesthetized rabbits. Right and left jugular vein segments were isolated by surgical technique for a 3 cm length, which included the bifurcation of the vessel, and left "in situ". Feiba(R) was injected through a marginal ear vein at the dose of 5 U/Kg/0.2 ml; 20 and 25 sec later the contralateral and the homolateral jugular vein segments were ligated respectively. Complete stasis lasted 10 or 20 min, then the vessels were removed, placed in a saline filled Petri dish and visually graded for red thrombus formation on a scale of 0 to 10. A correlation was found between severity of thrombosis and duration of stasis. This model appears to be suitable for testing heparin or heparin-like substances, in fact a linear correlation was found between log dose of the drug (injected i.v. 5 min before Feiba(R] and its antithrombotic effect for each duration of stasis tested. In particular the DE50 value calculated for 10 min stasis was 20.5 mcg/Kg i.v. The reproducibility of the model was good even with a small number of animals (n = 6) for each treatment group.