Funding for this study was provided by the University of Georgia's College of Veterinary Medicine and the American College of Veterinary Surgeons. A portion of the results from this study were presented at the International Veterinary Emergency and Critical Care Symposium held at Nashville, TN in September 2011.
Use of viscoelastic coagulation testing to monitor low molecular weight heparin administration to healthy horses
Article first published online: 8 MAY 2013
© Veterinary Emergency and Critical Care Society 2013
Journal of Veterinary Emergency and Critical Care
Volume 23, Issue 3, pages 291–299, May/June 2013
How to Cite
Tennent-Brown, B. S., Epstein, K. L., Whelchel, D. D. and Giguère, S. (2013), Use of viscoelastic coagulation testing to monitor low molecular weight heparin administration to healthy horses. Journal of Veterinary Emergency and Critical Care, 23: 291–299. doi: 10.1111/vec.12049
The authors declare no conflict of interest.
- Issue published online: 4 JUN 2013
- Article first published online: 8 MAY 2013
- Manuscript Accepted: 16 MAR 2013
- Manuscript Received: 24 JAN 2012
- University of Georgia's College of Veterinary Medicine
- American College of Veterinary Surgeons
- anticoagulant therapy;
To evaluate the utility of thromboelastography (TEG) and Sonoclot analyses to monitor the effects of low molecular weight heparin (LMWH) administration to healthy horses.
Randomized crossover study.
Large animal veterinary teaching hospital.
Six adult mixed breed healthy mares.
LMWH (dalteparin) was administered (50 U/kg subcutaneously) either every 12 or 24 h for 3 consecutive days. Blood samples were collected before LMWH administration and then at selected time points for analysis. Thromboelastography derived R-time (R), K-time (K), angle (ANG), and maximum amplitude (MA), and Sonoclot activated clot time (ACT), clot rate (CR), and platelet function (PF) were measured in whole blood 30 min after sample collection. Change (Δ) and percentage change (%Δ) from baseline of each TEG and Sonoclot variable were subsequently calculated. Anti-factor Xa activity and activated partial thromboplastin time (aPTT) were assayed in harvested plasma. The association between anti-factor Xa activity and TEG and Sonoclot (measured and calculated) variables was assessed by calculating correlation coefficients and multiple regression analysis. The ability of measured and calculated TEG and Sonoclot variables to predict when anti-factor Xa activity fell below suggested thromboprophylactic levels was assessed using receiver operating characteristic curve analysis.
Measurements and Main Results
The correlation between aPTT and anti-factor Xa activity was weak (r = 0.343). Changes in TEG and Sonoclot variables following LMWH administration were consistent with hypocoagulation. All measured and calculated TEG variables were significantly correlated with anti-factor Xa activity. Sonoclot ACT, ΔACT, CR, ΔCR, and %ΔCR were also significantly correlated with anti-factor Xa activity. TEG ΔR and %ΔR best predicted anti-factor Xa activity below the suggested thromboprophylactic level.
Although correlations were modest, serial measurement of TEG variables may be used to monitor LMWH therapy in horses; however, further research is required in sick horses.