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


METHODS
Prospective, experimental study.


METHODS
University-based research facility.


METHODS
Twelve healthy, adult, mixed-breed dogs.


METHODS
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.


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).


CONCLUSIONS
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.
Department of Small Animal Medicine and Surgery, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA. aralph@uga.edu
Alan G
AG
Ralph
Benjamin M
BM
Brainard
Jennifer R
JR
Pittman
Danielle M
DM
Babski
Amie
A
Koenig
D000818:Animals; D001800:Blood Specimen Collection / Q000379:methods / Q000662:veterinary*; D004285:Dogs / Q000097:blood*; D005260:Female; D008297:Male; D011446:Prospective Studies; D013696:Temperature; D013916:Thrombelastography / Q000379:methods / Q000662:veterinary*; D013997:Time Factors