Evaluation of Tissue Factor and Kaolin Activated Thromboelastography on Feline Citrated Whole Blood From Clinically Healthy Cats
ACVIM 2008
C.R. Bjornvad; B. Wiinberg; A.L. Jensen; A.T. Kristensen
Department of Small Animal Clinical Sciences, University of Copenhagen
Denmark

Thromboelastography (TEG) enables global assessment of hemostatic function in whole blood with evaluation of both plasma and cellular components during initiation, amplification and propagation of clot formation. TEG is routinely used in the diagnostic workup and monitoring of humans and dogs with hemostatic disorders and it has shown to be a valuable supplement to the traditional coagulation parameters such as platelet count, PT, APTT, fibrinogen and D-dimer currently used in most clinical pathology laboratories.

The objective of this study was to evaluate a human recombinant tissue factor (TF) and a Kaolin (K) activated TEG assay on citrated whole blood (WB) from clinically healthy cats, with the aim of estimating reference ranges for physiological hemostasis in healthy cats.

Citrated WB was collected from 17 clinically healthy cats and stored at RT for 30 min before analysis. Duplicate TEG analyses with TF (1:50,000) or Kaolin as activator were performed. R, K, α and MA were analyzed. Distribution of the data was assessed with the D'Agostino and Pearson omnibus normality test. A paired t-test was applied to identify any significant difference in R, K, α and MA between TF and K activation. Statistical significance was set at p < 0.05.

The observed TEG parameters (median (range)) for TF were: R = 8.95 min (5.00-14.35), K = 5.85 min (3.33-15.05), α = 29.9o (18.3-50.7)and MA=39.9 mm (24.6-54.1). With kaolin activation the TEG parameters were: R = 9.00 min (3.80-14.80), K = 4.85 min (1.85-7.65), α = 38.5o (26.8-62.1)and MA=47.1 mm (34.9-57.7). Using TF or K as activators, significant differences were observed for the TEG parameters K, α and MA (P<0.05) but not R, indicating similar activation time but enhanced clotting kinetics and clot strength with kaolin activation.

In conclusion, feline citrated WB can be used for TEG analysis with TF or K as activators. However, in this study, Kaolin seems to activate coagulation processes more than human recombinant tissue factor. Coagulation activation and kinetics of feline WB in the TEG assay differ from references in dogs, the coagulation reaction starts later and develops slower in cats. Further studies on coagulation kinetics in cats are in progress.

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Charlotte Bjornvad


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