Clot formation in canine whole blood as measured by rotational thromboelastometry is influenced by sample handling and coagulation activator

Abstract

The objective of the present study was to systematically evaluate the impact of methodology on thromboelastometry with canine whole blood. Thromboelastometry was performed on citrated blood using a variety of combinations of clotting activators [ex-tem (tissue factor or TF), in-tem (ellagic acid), diluted TF from Innovin, or Ca (recalcification only)] and storage times. Thromboelastometry was also performed using diluted TF from Innovin on blood collected into a contact inhibitor. Ex-vivo contact activation was compared between canine and human blood. Clotting activator had a marked impact on coagulation time, a minor impact on alpha angle, and no impact on clot formation time or maximum clot firmness. When ex-tem or in-tem was the clotting activator, sample storage up to 30 min did not affect results. With diluted TF from Innovin or Ca, sample storage was associated with the development of increased coagulability (as indicated by shorter coagulation time and clot formation time and higher alpha angle) due to ex-vivo contact activation. Canine blood underwent markedly more ex-vivo contact activation than did human blood. Canine blood undergoes significant ex-vivo contact activation during and after collection, which influences thromboelastometry results when a weak clotting activator (such as low TF or recalcification) is used. Thromboelastometry with a strong activator (such as ex-tem or in-tem) is less influenced by ex-vivo changes, and, therefore, likely to be more reflective of in-vivo hemostatic capabilities and to provide consistently interpretable and comparable results.

Comparison of the effects of 7.2% hypertonic saline and 20% mannitol on whole blood coagulation and platelet function in dogs with suspected intracranial hypertension - a pilot study

“…Whole blood coagulation was analyzed using ROTEM® (ROTEM®, TEM Innovations GmbH, Munich, Germany), according to the manufacturer’s instructions using methods previously described for canine samples [24]. Two ROTEM® machines were available to enable parallel measurements of T 0 and T 5 samples.…”

Evaluation of thromboelastography in two factor XII-deficient cats

“…9–11 Similar results have been reported in canine studies when corn trypsin inhibitor is used to inhibit FXII activity. 5,12 …”

Thromboelastometry used for evaluation of blood coagulability in dogs with kidney diseases

“…Shortening of CT is suggestive of more rapid fibrin formation. This indicator is profoundly impacted by the activator used, whereas the other variables are less or minimally influenced (Smith et al 2010). With the use of in-TEM or ex-TEM reagents, the two coagulation pathways can be investigated separately because initial thrombin formation occurs exclusively via the intrinsic or the extrinsic pathway, respectively.…”

“…With the use of in-TEM or ex-TEM reagents, the two coagulation pathways can be investigated separately because initial thrombin formation occurs exclusively via the intrinsic or the extrinsic pathway, respectively. Furthermore, the use of strong activators decreases the impact of sample changes occurring prior to initiation of the analysis, so that the results are more easily repeatable (Smith et al 2010).…”

“…A recent study has identified hypercoagulability by means of non-activated TEG in 7 dogs affected by renal failure and in 11 dogs with severe proteinuria (Donahue et al 2011). Thromboelastometry on canine whole blood has also been recently validated (Smith et al 2010).…”