title: Evaluation of a modified thrombelastography assay initiated with recombinant human tissue factor in clinically healthy horses.
abstract: 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.
authors: Department of Clinical Sciences, Faculty of Veterinary Medicine, Universite de Montréal, Saint-Hyacinthe, QC, Canada.
authors: Mathilde
authors: M
authors: Leclere
authors: Jean-Pierre
authors: JP
authors: Lavoie
authors: Marilyn
authors: M
authors: Dunn
authors: Christian
authors: C
authors: Bédard
mesh_terms: 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
chemical_list: D002951:Citrates; D011994:Recombinant Proteins; D013925:Thromboplastin