Get access

Pharmacodynamics of Multi-Dose Low Molecular Weight Heparin in Healthy Horses

Authors

  • Dorothy D. Whelchel DVM, MS,

    1. Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia
    Search for more papers by this author
  • Brett S. Tennent-Brown BVSc, MS, Diplomate ACVIM & ACVECC,

    Corresponding author
    • Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia
    Search for more papers by this author
  • Steeve Giguère DVM, PhD, Diplomate ACVIM,

    1. Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia
    Search for more papers by this author
  • Kira L. Epstein DVM, Diplomate ACVS & ACVECC

    1. Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia
    Search for more papers by this author

  • A portion of the results from this study was presented at the International Veterinary Emergency and Critical Care Symposium held at San Antonia, TX, September 2010.

Corresponding Author

Brett Tennent-Brown, BVSc, MS, Diplomate ACVIM & ACVECC, Faculty of Veterinary Science—Equine Center, University of Melbourne, 250 Princes Highway, Werribee, VIC 3030, Australia. E-mail: bretttbrown@gmail.com

Abstract

Objectives

To compare the pharmacodynamics of once daily and twice daily administration of low molecular weight heparin (LMWH) administration in horses.

Study Design

Randomized cross over study.

Animals

Adult mixed breed healthy mares (n = 6).

Methods

LMWH (dalteparin) was administered (50 U/kg subcutaneously) either every 12 or 24 hours for 3 consecutive days. Anti-factor Xa activity was measured before and at select time points after LMWH administration. Packed cell volume (PCV), platelet count, partial thromboplastin time (PTT), and anti-thrombin (AT) activity were monitored throughout the study.

Results

No changes in PCV, platelet count, or AT activity were detected with either frequency of daily LMWH administration. Values for PTT increased throughout the study but never exceeded the normal reference interval. Anti-factor Xa activity was maintained within or above the suggested thromboprophylactic range (0.1–0.2 U/mL) when LMWH was administered twice daily, but fell below this range ∼16 hours after administration when given once daily. For both once and twice daily LMWH administration, the area under the curve was significantly greater after the last dose of LMWH when compared to the first dose.

Conclusions

Administration of LMWH once or twice daily for 3 consecutive days appears to be safe in healthy adult horses. Anti-factor Xa activity was maintained within or above the suggested thromboprophylactic range for 24 hours with twice daily LMWH administration but not with once daily administration.

Get access to the full text of this article

Ancillary