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

backgroundThrombin 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.

objectivesTo compare standard CAT methodology to a low plasma and low reagent volume CAT method in dogs.

methodsPlatelet-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.

resultsThere 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.

conclusionsBased 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.