title: Thromboelastographic monitoring of the effect of unfractionated heparin in healthy dogs.
abstract: OBJECTIVE
  To characterize the correlation between thromboelastography (TEG) variables using strong activators and anti-Xa (AXa) activity in healthy dogs administered subcutaneous unfractionated heparin (UFH).
  
  
  METHODS
  Prospective experimental study.
  
  
  METHODS
  University research facility.
  
  
  METHODS
  Eight adult random-source male dogs.
  
  
  METHODS
  Dogs were randomized to receive subcutaneous UFH at 200, 250, or 300 IU/kg every 8 hours for a total of 10 injections. Blood samples were collected at time 0 (preheparin) and 3, 6, and 8 hours after the 1st (Day 1) and 10th (Day 4) UFH injection.  After the 8-hour blood sample was obtained on day 4, a 100 IU/kg IV bolus of UFH was administered and an additional blood sample was collected 1 hour later (hour 9). AXa activity, activated partial thromboplastin time (aPTT), and TEG (with up to 5 activators) were performed at each time point.  Modes of activation for TEG included  recalcified (Ca), Ca with heparinase (CaH), CaH and tissue factor 1:3600 (CTF3600H), Ca with tissue factor 1:100 (CTF100), and RapidTEG. Spearman rank correlations were calculated for each of the aforementioned parameters and the AXa activity. P-values were corrected for multiple comparisons with a Bonferroni correction.
  
  
  RESULTS
  Significant correlations were found between AXa activity and the TEG R values generated with CTF100 (R = 0.83, P ≤ 0.0001) and RapidTEG (R = 0.90, P < 0.0001), as well as both forms of aPTT measurement (R = 0.86 and 0.84, P < 0.0001).
  
  
  CONCLUSIONS
  This study demonstrates that TEG variables derived using robust activation correlate with AXa activity as well as aPTT and have the potential to be used for monitoring UFH therapy in healthy dogs.  Future studies are warranted to evaluate its diagnostic utility in critically ill animals.
authors.affiliation: Department of Clinical Sciences, North Carolina State University College of Veterinary Medicine and the NCSU Bioinformatics Research Center, Raleigh, NC, 27606.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: McLaughlin
authors.affiliation: Department of Clinical Sciences, North Carolina State University College of Veterinary Medicine and the NCSU Bioinformatics Research Center, Raleigh, NC, 27606.
authors.forename: Steven L
authors.initials: SL
authors.lastname: Marks
authors.affiliation: Department of Clinical Sciences, North Carolina State University College of Veterinary Medicine and the NCSU Bioinformatics Research Center, Raleigh, NC, 27606.
authors.forename: David C
authors.initials: DC
authors.lastname: Dorman
authors.affiliation: Department of Statistics, NCSU College of Physical and Mathematical Sciences, North Carolina State University, Raleigh, NC, 27606.
authors.forename: Alison
authors.initials: A
authors.lastname: Motsinger-Reif
authors.affiliation: Department of Clinical Sciences, North Carolina State University College of Veterinary Medicine and the NCSU Bioinformatics Research Center, Raleigh, NC, 27606.
authors.forename: Rita M
authors.initials: RM
authors.lastname: Hanel
mesh_terms: D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects*; D004285:Dogs; D005260:Female; D006493:Heparin / Q000008:administration & dosage / Q000494:pharmacology*; D007279:Injections, Subcutaneous / Q000662:veterinary; D008297:Male; D010314:Partial Thromboplastin Time / Q000662:veterinary; D011446:Prospective Studies; D012016:Reference Values; D013916:Thrombelastography / Q000662:veterinary
chemical_list: D000925:Anticoagulants; D006493:Heparin
keywords: RapidTEG; anti-Xa; anticoagulation monitoring; canine; thrombosis