Introduction & background: Viscoelastic coagulometers can detect hypercoagulability and hyperfibrinolysis. Greyhound dogs possess unique coagulation characteristics that are uncommon in other breeds.

Objective: To measure viscoelastic coagulation in two canine blood donor populations using a novel, point-of-care coagulometer (VCM) and correlate the results to CBC data.

Methods: Healthy non-Greyhound (Group 1) and Greyhound dogs (Group 2) were enrolled after IACUC approval. Dogs with missing data, blood cell concentrations below reference intervals, or undetected VCM values were excluded. Venous whole blood was analyzed on the VCM and a unique cytometer for each group.

Statistics (significance set at p<0.05) were completed using a commercial statistics program. To look for differences in CBC and VCM parameters, a t-test or a Wilcoxon rank-sum test were completed as appropriate.

Results: CBC data (mean[SD]): Group 1 (n=39, 12 breeds) demonstrated the Hgb concentration (17.1gm/dL [1.7]), RBC concentration (RBC, 7.7x106/microliter [5.7]), white blood cell concentration (WBC 7420x103/microliter [1898]), and platelet concentration (Plt, 206x103/microliter [48]). Group 2 (n=54 Greyhound dogs) showed Hgb (18.1 g/dL [2.5]), RBC (9.5x106/microliter [1.4]), WBC (10022x103/microliter [2279]), and Plt 262103/microliter[99]). There is a statistical difference between all CBC values between Groups 1 and 2. VCM data (mean[SD]): Group 1 were clot time (CT, 288.7 s [84.6]), CFT (255.9 s [102.5]), AA (51.2 degrees [8.4]), maximum clot firmness (MCF, 26.0 VCM units [5.7]), LI30 (86.4% [21.0] ), LI45 (84.9% [24.7]). Group 2 were CT (275.6 s [51.7]), CFT (299.7 s [433.6]), AA (50.3 degrees [8.1]), MCF (17.0 VCM units [4.5]), LI30 (29.4% [13.8]), LI45 (27.1% [12.8]). Statistical differences exist between groups for MCF, LI30, and LI45.

Discussion: Greyhound dogs in Group 2 have higher Hgb than all other breeds in Group 1. The other differences in CBC data unlikely impact the overall viscoelastic assessment. Initial measurements of fibrin formation (CT, CFT, & AA) were similar between groups. The MCF, LI30 & LI45 are profoundly different demonstrating that Greyhounds have weaker overall clot strength and larger and consistent fibrinolysis compared to non-Greyhound dogs. The difference in Plt may have some impact on MCF, but the hyperfibrinolysis cannot be explained by any other measured parameter.

Conclusions: The VCM Vet clearly demonstrates hyperfibrinolysis in healthy Greyhound blood donors compared to non-Greyhound blood donor dogs.