Viscoelastic Coagulation Monitor (VCM^Vet) Reference Intervals and Sex Differences in Mature Adult Mice

Viscoelastic coagulation tests are useful to assess coagulation status in the clinical setting and to aid in understanding underlying pathophysiological mechanisms that affect coagulation status. Such tests also are useful for coagulation research. Because mouse models are widely used to study molecular mechanisms in fine detail, a simple viscoelastic coagulation test requiring small blood volumes would be convenient for such studies in mice. Methods: We tested viscoelastic coagulation properties of normal healthy adult mice using a novel veterinary clinical point-of-care device, Viscoelastic Coagulation Monitor (VCM Vet™; Entegrion Corp.). Fresh whole blood was collected from 63 healthy mature adult C57 black 6N mice, with ultimately 54 mice, equal numbers of male and females, used to determine reference intervals (RIs) for VCM test parameters. Results: RIs were determined for equal numbers of male and female mice: clot time: 43.0–353.0 s; clot formation time: 49.4–137.6 s; alpha angle: 54.4–62.2°; A10: 25.0–49.6 VCM units; A20: 31.0–56.5 VCM units; maximum clot firmness: 37.6–62.8 VCM units; Lysis Index 30 (Li30): 99.8–100.0%; and Li45: 99.7–100.0%. Significant differences were found between male and female subgroups, where females had higher mean A10 and A20 and median MCF values, indicating greater clot firmness in female versus male mice. Conclusion: VCM Vet is a feasible viscoelastic coagulation test device for studies with mature adult mice, including studying inherent sex differences in coagulation parameters. Inherent differences in coagulability of male and female mice warrant further investigation to determine if such differences underlie greater coagulopathic, hemorrhagic, or thromboembolic risk during trauma or other pathophysiologic conditions.