Troubleshooting the rabbit ferric chloride-induced arterial model of thrombosis to assess in vivo efficacy of antithrombotic drugs.

Introduction: The FeCl3-induced arterial model of thrombosis is one of the most widely used animal models to assess arterial efficacy of new antithrombotic drug candidates. This model is well-established in rodents but in a less extent in the rabbit. In this work, we present a methodology for a rabbit FeCl3-induced arterial model of thrombosis derived from our troubleshooting which allows the generation of reliable efficacy data for new antithrombotic drug candidates.

Methods: Rabbits were administered with heparin 4.5U/kg/min, argatroban 10μg/kg/min or saline by intravenous infusion. The blood flow was monitored using a Doppler flow probe. The time from the application of FeCl3 to the recorded zero blood flow was defined as the time to occlusion, with a maximum recording time of 60min post-FeCl3 application. After 30min of infusion, thrombosis was induced by wrapping a FeCl3-saturated filter paper around the carotid artery caudal to the flow probe. Animals were subject to exclusion criteria based on the visual aspect of the artery FeCl3-induced injury and based on changes in blood flow upon FeCl3 application.

Results: Following the application of FeCl3, a mean time to occlusion for saline, heparin and argatroban of 24.3±1.8, 52.5±4.8 and 53.5±4.5min was obtained, respectively. Mean time to occlusion for heparin and argatroban administered groups was significantly different when compared to the saline-treated group (p<0.05). These results for the test compounds represent approximately 80% of the maximum possible prolongation.

Discussion: The rabbit FeCl3-induced arterial model of thrombosis presented in this paper derived from our troubleshooting is sensitive and reproducible for the generation of accurate and reliable efficacy data in the assessment of new antithrombotic agents in preclinical drug development.