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Effects of rest temperature, contact activation, and sample technique on canine thrombelastography


  • Alan G. Ralph DVM,

    Corresponding author
    • Department of Small Animal Medicine and Surgery, University of Georgia College of Veterinary Medicine, Athens, GA
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  • Benjamin M. Brainard VMD, DACVECC, DACVA,

  • Jennifer R. Pittman DVM, DACVECC,

  • Danielle M. Babski DVM,

  • Amie Koenig DVM, DACVECC, DACVIM

  • Dr. Brainard is an assistant editor of the Journal but did not participate in the peer review process other than as a co-author. The authors declare no other conflict of interest.

  • Portions of this work have been presented in abstract form at the 28th Annual ACVIM Forum, June 10, 2010 and at the 16th Annual IVECCS, September 11–15, 2010.

Address correspondence and reprint requests to

Dr. Alan G. Ralph, DVM Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA.




To determine the effects of rest temperature, contact activation (CA), and sample collection technique on thrombelastography (TEG) using canine whole blood.


Prospective, experimental study.


University-based research facility.


Twelve healthy, adult, mixed-breed dogs.


Blood was collected by jugular venipuncture. Tubes containing 3.2% sodium citrate, with and without 75 μg/mL corn trypsin inhibitor (CTI), were filled by vacuum. Samples rested for 30 minutes at 3 temperatures: 37°C, room temperature (RT, 20–22°C), or warmed to 37°C 5 minutes prior to analysis (prewarmed). Samples were analyzed at 37°C. CTI-treated samples were analyzed with and without 1:50,000 tissue factor (TF) as activator. Six dogs were also tested similarly using a needle/syringe collection technique.

Measurement and Main Results

Prewarmed samples exhibited greater MA compared to RT (55.5 ± 7.2 mm vs. 53.5 ± 6.0, P< 0.05), while 37°C samples exhibited a steeper angle (56.7 ± 10.4°C vs. 52.4 ± 8.6°C) and greater MA (55.9 ± 7.5 mm vs. 53.5 ± 6.0 mm) than RT samples (both P< 0.05). CTI-treated samples were hypocoagulable (R time 45 min [7.5–56.8 min], angle 8.2°C [5.1–42.5°C], MA 29.2 ± 9.7 mm, P< 0.001), with TF activation returning all but the angle (42.5 ± 7.6°C) to values similar to citrated samples (angle = 56.7 ± 10.4°C, P = 0.017). Collection using a syringe/needle method revealed a shorter R time for prewarmed samples only (R time 4.7 ± 0.7 min, vs. 5.6 ± 0.8 min for vacuum-collected samples, P = 0.008).


Even in the absence of exogenous activators, CA has an impact on canine TEG results. The effects of rest temperatures and sample collection technique on TEG appear to be minimal.