Preliminary evaluation of reference intervals for a point-of-care viscoelastic coagulation monitor (VCM Vet) in healthy adult horses

Objective: To evaluate a point-of-care viscoelastic coagulation monitor (VCM Vet) for use in horses by assessing variability between devices and establish reference intervals (RIs) for healthy adult horses. Design: Prospective observational study. Setting: Two university teaching hospitals. Animals: Healthy adult horses (n = 68). Interventions: None. Measurements and Main Results: Blood collected by direct jugular venipuncture was applied directly from the syringe into 2 VCM Vet cassettes to establish coefficients of variation (CVs) and RIs for reported parameters of clotting time (CT), clot formation time (CFT), alpha angle, amplitude at 10 and 20 minutes, maximum clot firmness, and lysis index at 30 and 45 minutes. CVs for each parameter were within clinical tolerance. There was a significant difference in CT between institutions (P < 0.001). Differences in CV were found between institutions for CT (P = 0.003) and CFT (P = 0.01). Healthy horse RIs were calculated for the overall data set and each individual institution. Calculated RIs were as follows: CT, 255.6–1233.9 seconds; CFT, 89.4–581 seconds; alpha angle, 11.4–53.6°; maximum clot firmness, 18–37.7; lysis index at 30 minutes, 97.3%–102.1%; lysis index at 45 minutes, 80.8%–103.3%; amplitude at 10 minutes, 8.7–28.3; and amplitude at 20 minutes, 17.4–35.7. Conclusions: VCM Vet is a repeatable and practical option for rapid point-of-care assessment of hemostasis in horses but has a wide RI and is susceptible to variability. Establishment of institution-specific RIs is recommended.