Thromboelastographic tracings in retired racing greyhounds and in non-greyhound dogs

Background: Bleeding disorders in patients with normal coagulation test results are frequently reported in Greyhounds. The purpose of this study was to compare Greyhounds to non-Greyhounds by thromboelastography (TEG). Hypothesis: TEG parameters in Greyhounds are different from those in non-Greyhounds. Animals: Forty-three healthy dogs (28 Greyhounds and 15 non-Greyhounds) based on the results of physical examination, CBC, activated partial thromboplastin time, prothrombin time, fibrinogen, and platelet count. Materials and Methods: Recalcified citrated native TEGs were performed in both groups; data were compared using Student's, Mann-Whitney, and Pearson's statistical tests. Results: In Greyhounds, mean +/- SD were as follows: R-time 4.3 +/- 1.7 minutes, K-time 3.8 +/- 1.4 minutes, angle (alpha) 50.0 +/- 8.0 degrees, maximum amplitude (MA) 47.6 +/- 5.6 mm, clot strength (G) 4,647 +/- 1,097 dyn/cm(2), and percent lysis at 60 minutes (LY60) 2.8 +/- 5.0%. In the non-Greyhounds they were R-time 3.7 +/- 1.6 minutes, K-time 2.5 +/- 0.9 minutes, angle 59.8 +/- 7.0 degrees, MA 53.1 +/- 5.6 mm, G 5,811 +/- 1,256 dyn/cm(2), and LY60 3.1 +/- 2.5%. All parameters were significantly different between the groups, except for R-time and LY60. Conclusion: In Greyhounds, clotting kinetics are slower and clot strength are weaker than in non-Greyhounds, supporting the increased tendency to bleed observed after minor trauma or surgical procedures in the breed. The findings may also be attributed to blood viscosity or to the concentration of citrate in the sample (ie, Greyhounds have higher hematocrit and less plasma per unit volume).