title: Pharmacodynamics of multi-dose low molecular weight heparin in healthy horses.
abstract: OBJECTIVE
  To compare the pharmacodynamics of once daily and twice daily administration of low molecular weight heparin (LMWH) administration in horses.
  
  
  METHODS
  Randomized cross over study.
  
  
  METHODS
  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.
authors.affiliation: Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, Georgia, USA.
authors.forename: Dorothy D
authors.initials: DD
authors.lastname: Whelchel
authors.forename: Brett S
authors.initials: BS
authors.lastname: Tennent-Brown
authors.forename: Steeve
authors.initials: S
authors.lastname: Giguère
authors.forename: Kira L
authors.initials: KL
authors.lastname: Epstein
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects; D017985:Dalteparin / Q000009:adverse effects / Q000097:blood / Q000494:pharmacology*; D005260:Female; D006736:Horses / Q000097:blood*
chemical_list: D000925:Anticoagulants; D017985:Dalteparin