Research Note: Hemostasis & Ehrlichia canis Infection

Ehrlichia canis infection causes thrombocytopenia and clinical bleeding in dogs, although some dogs with clinically relevant thrombocytopenia will not show signs of bleeding. In this study, hemostatic variables, platelet dynamics, and coagulation testing were evaluated before inoculation of dogs with blood infected with E canis, then at 1-week intervals, including after treatment with doxycycline between weeks 3 and 4. Infected dogs were found to have significantly lower platelet counts, evidence of activated platelets, and antiplatelet antibodies. Based on thrombo-elastographic measurements, dogs were also more hypercoagulable and hypofibrinolytic as compared with baseline. Although more studies are needed, results suggest that activated platelets and a hypercoagulable, hypofibrinolytic state may explain the lack of a bleeding phenotype in some thrombocytopenic dogs infected with E canis.