Evaluation of a modified thrombelastography assay initiated with recombinant human tissue factor in clinically healthy horses.
BACKGROUND
Thrombelastography (TEG) is used to evaluate the viscoelastic properties of blood during clotting and provides a global assessment of hemostasis and clot lysis. TEG analysis initiated with recombinant human tissue factor (TF) has not been evaluated in clinically healthy horses.


OBJECTIVE
The purpose of this study was to determine whether TEG results are affected by the time elapsed between sampling and analysis (storage time) of equine blood samples and to establish a preliminary equine reference interval for a modified TEG assay, using recombinant human TF to initiate coagulation.


METHODS
Citrated blood samples were obtained from 20 clinically healthy adult horses. Thirteen samples were stored for 30, 60, and 120 minutes at room temperature before TEG analysis. Coagulation was initiated by adding 20 microL of CaCl(2) to 330 microL of blood and 10 microL of diluted recombinant TF for a final dilution of 1:3600. Reaction (R) and clotting (K) times, angle (alpha), and maximum amplitude (MA) were compared between time points. A preliminary reference interval (minimum-maximum values) was determined using data from all 20 horses after 30 minutes of sample storage.


RESULTS
There was a significant effect of storage time on R, K, and alpha but not MA. Reference intervals were: R, 3.65-6.4 minutes; K, 1.8-5.45 minutes; alpha, 33.4-66.2 degrees ; MA, 41.2-64.1 mm; lysis at 30 minutes post-MA (LY30), <2.75%; and lysis at 60 minutes post-MA (LY60), 1.55-9.5%.


CONCLUSIONS
TEG can be performed on equine citrated blood samples using recombinant human TF to activate clot formation. TEG parameters were significantly affected by storage time, suggesting an incomplete inhibition of coagulation in citrated blood.
Leclere
Mathilde
M
Department of Clinical Sciences, Faculty of Veterinary Medicine, Universite de Montréal, Saint-Hyacinthe, QC, Canada.
Lavoie
Jean-Pierre
JP
Dunn
Marilyn
M
Bédard
Christian
C
D000818:Animals; D001777:Blood Coagulation / Q000502:physiology*; D001780:Blood Coagulation Tests / Q000379:methods / Q000662:veterinary; D002951:Citrates; D005260:Female; D006487:Hemostasis; D006736:Horses / Q000097:blood*; D006801:Humans; D008297:Male; D011994:Recombinant Proteins; D012016:Reference Values; D013048:Specimen Handling / Q000662:veterinary*; D013916:Thrombelastography / Q000379:methods / Q000662:veterinary*; D013925:Thromboplastin / Q000737:chemistry*; D013997:Time Factors
D002951:Citrates; D011994:Recombinant Proteins; D013925:Thromboplastin