Assessment of hemostasis using thromboelastography (TEG) has received much attention recently, with adoption as a diagnostic tool in many referral and institutional centers. This seminar will review the application of this test for canine and feline patients, and present a review of the current literature on the topic.Numerous variables can be derived from the TEG tracing (Figure 1), but only a few are commonly used routinely. There are four standard variables that relate to clot formation. The reaction time or R time, measures the time in minutes from initiation of the test to first formation of fibrin and amplitude of 2mm. This is the usual endpoint of traditional plasma based tests, and becomes prolonged when there is a decrease in clotting factor activity. The K time measures the time in minutes from amplitude of2mm to 20mm, and is a representation of speed of clot formation. Alpha (commonly a or angle") is a measure in degrees of the angle tangential to the developing curve as K is reached. Finally, the maximum amplitude, or MA, is a measure in millimeters ofthe maximal amplitude reached and is an assessment of maximal clot strength, and overall stability of the clot. Additionally, G can be used as an assessment of clot strength, and is a derivative of MA in dynes/cm . Clot lysis variables LY30 and LY60 canbe determined if the tracing is allowed to run long enough, and are percent lysis at 30 and 60 minutes respectively, after determination of MA.
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