A reproducible rat model for warfarin studies: Prothrombin time assessment with minimal blood using the CoaguChek XS and determination of an effective warfarin dosage

Warfarin research inrats isoften challenged bymethodological inconsistencies and large blood volume requirements. This study aimed tovalidate arefined, reproducible rat model for serial prothrombin time (PT) monitoring using the CoaguChek XS, inalignment with the 3R principles, and todetermine aneffective warfarin sodium dosage. Male Wistar albino rats received daily oral warfarin (0.125–0.750mg/kg) for 5days. PT was measured using the whole-blood CoaguChek XS and two laboratory plasma assays (Innovin, ThromborelS). Agreement was assessed using Bland–Altman and Passing–Bablok regression. The CoaguChek XS consistently yielded higher PT values than laboratory tests but showed strong agreement up to25seconds. Adaily dose of0.125mg/kg resulted inastable anticoagulant effect without mortality. Doses Doses of0.250mg/kg and higher were toxic, causing PT prolongation beyond the device’s range and high mortality within 4–7days after the initiation oftreatment. Inconclusion, the CoaguChek XS isareliable tool for experiments requiring repeated measurements. Values remain reliable upto25s, and 0.125 mg/kg is a safe dose for short-term studies, effectively supporting animal welfare and the 3R principles.