Comparison of the Calibrated Automated Thrombogram Using Standard and Low Plasma Volumes in Dogs

ABSTRACT Background Thrombin generation assessment using calibrated automated thrombography (CAT) requires a standard volume of plasma (80 μL) and reagent (20 μL) run in triplicate. A CAT method using lower plasma and reagent volumes could benefit veterinary patients as it lowers the sampling burden in patients. Objectives To compare standard CAT methodology to a low plasma and low reagent volume CAT method in dogs. Methods Platelet‐poor plasma samples were obtained by direct jugular venipuncture in dogs with low (n = 10), high (n = 10), and normal (n = 10) thrombin generation potential, recruited from a tertiary referral hospital. Method comparison was performed between standard CAT (80 μL plasma, 20 μL reagent‐ method 1) and low volume CAT (40 μL plasma, 10 μL reagent‐ method 2). Lag time (lag time); endogenous thrombin potential (ETP); peak (peak); and time to peak (ttpeak) were assessed on the thrombin generation curves. Results There was excellent agreement between methods 1 and 2 for all parameters. Lin's concordance coefficients were 0.97, 0.94, 0.96, and 0.96 for lag time, ETP, ttpeak, and peak, respectively. There was a small bias for all parameters (p < 0.05), resulting in a significant change for lag time only. There was a significant predictive linear equation that, when modeled, allowed the conversion of method 2 to method 1 values. The methods had similar variation when measuring TG variables. Conclusions Based on the results in this small group of dogs, we conclude that low‐volume CAT appears to be an alternative to the standard testing method in dogs.