Characteristics of hemostasis during experimentalEhrlichia canisinfection

Abstract

Background Ehrlichia canis infection in dogs can cause thrombocytopenia and clinical evidence of bleeding. It is unknown why some dogs show signs of bleeding whereas others do not despite clinically relevant thrombocytopenia.Hypothesis/ObjectivesActivated platelets, decreased fibrinolysis or both mitigate bleeding tendency. Assess standard hemostatic variables, platelet dynamics, and specialized coagulation testing in dogs experimentally infected with E. canis to evaluate this clinical discrepancy.AnimalsFour healthy laboratory beagles.MethodsDogs were given blood infected with E. canis IV. Platelet indices of activation, platelet aggregometry, antiplatelet antibodies (percent IgG), complete coagulation panel, and thromboelastography (TEG) were measured before inoculation and on weeks 1‐8. Dogs were treated with doxycycline at approximately 5 mg/kg PO q12h between weeks 3 and 4 (day 24). For each variable, 1‐way repeated measures analysis (1‐way ANOVA) with post‐hoc analysis was performed with statistical significance set at P < .05.ResultsDogs had significantly lower platelet counts, evidence of activated platelets, and antiplatelet antibodies during E. canis infection. Dogs also appeared hypercoagulable and hypofibrinolytic using TEG as compared with baseline, changes that persisted for variable amounts of time after doxycycline administration. No overt signs of bleeding were noted during the study.Conclusions and Clinical ImportanceActivated platelets and a hypercoagulable, hypofibrinolytic state could explain the lack of a bleeding phenotype in some dogs despite clinically relevant thrombocytopenia. Findings from our pilot study indicate that additional studies are warranted.

Effects of canine influenza infection and DA2PP vaccination on the development of platelet‐associated immunoglobulins and platelet counts in dogs

“…The client‐owned animals assessed in this study were approved by the Colorado State University Clinical Review Board (VCS #2019‐231), and all owners signed a consent form. For the client‐owned animal experiment, a sample size of 5 dogs per vaccine group was determined by power calculation using the results from experiment 1 and the reported incidence of ITP following MMR vaccination in children 16 . However, since this vaccine is part of routine health care, the Clinical Review Board approved increasing to 10 dogs for each vaccine group to increase the chances of finding an effect, if present.…”

“…[33][34][35][36] However, platelet count alone is a poor predictor of bleeding, and some dogs with severe thrombocytopenia do not bleed, likely as a result of various factors, including decreased fibrinolytic activity, presence of large activated platelets, and hypercoagulable state from concurrent infections or systemic inflammation. 16,37,38 Management and prognosis of thrombocytopenia depend on severity, comorbidities, and underlying etiology. The presence or absence of PAIg can help guide clinicians in determining the underlying mechanism of thrombocytopenia and the appropriate next diagnostic and therapeutic steps.…”

“…As such, a positive PAIg classification has the potential to be misleading if interpreted inappropriately. 1,[10][11][12][13][14][15][16] With the increasing accessibility of PAIg testing in dogs, understanding how to interpret the results is vital.…”

“…Most dogs with primary ITP have detectable PAIg; 1,7‐9 however, their presence does not identify the etiology of the immunoglobulins, nor does it distinguish between primary and secondary causes of ITP. As such, a positive PAIg classification has the potential to be misleading if interpreted inappropriately 1,10–16 . With the increasing accessibility of PAIg testing in dogs, understanding how to interpret the results is vital.…”

Platelet function in dogs with chronic liver disease

“…In dogs, TEG is usually employed to assess for potential coagulopathies and hypercoagulable states. Thromboelastography has been evaluated in dogs with a variety of diseases, such as chronic hepatopathies 53 , chronic kidney disease 54 , immunemediated hemolytic anemia 55 , and dogs infected with Ehrlichia canis 56 . It has also been used to assess coagulation changes in response to treatment with medications, such as rivaroxaban 57 and Yunnan Baiyo 45 .…”