A mouse bleeding model to study oral anticoagulants.

New oral anticoagulants to reduce the incidence of thrombosis have recently become available. When compared to the existing therapy, warfarin, these novel agents have similar efficacy with a reduced risk of spontaneous bleeding. However, these novel agents have been associated with significant, even fatal, bleeding following trauma. Reversal agents are being developed that bind and neutralize these oral anticoagulants. However, these are not yet available. Another strategy is to increase thrombin generation by administration of "bypassing" agents such as prothrombin complex concentrates or factor VIIa. Several animal models have been used to model the hemostatic defect induced by the thrombin inhibitor dabigatran. A rat tail injury model, a rabbit cuticle bleeding model, and a rabbit kidney laceration model have all been reported to show increased bleeding, but with supratherapeutic doses of dabigatran. A mouse tail transection model has been reported to reflect increased bleeding at peak therapeutic dabigatran levels. We found that the Whinna saphenous vein hemostasis model reliably reflects a hemostatic defect at therapeutic levels of dabigatran. This model can potentially reflect the effects of reversal or bypassing agents.