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&#x2009;&#x3bc;L) and reagent (20&#x2009;&#x3bc;L) 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&#x2009;=&#x2009;10), high (n&#x2009;=&#x2009;10), and normal (n&#x2009;=&#x2009;10) thrombin generation potential, recruited from a tertiary referral hospital. Method comparison was performed between standard CAT (80&#x2009;&#x3bc;L plasma, 20&#x2009;&#x3bc;L reagent- method 1) and low volume CAT (40&#x2009;&#x3bc;L plasma, 10&#x2009;&#x3bc;L 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&#x2009;<&#x2009;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.