Abstract:
Dogs with Babesia rossi infection display a normocoagulable thromboelastogram, despite being markedly thrombocytopenic. This is purportedly due to large-scale platelet activation. Thromboelastographic platelet mapping (TEG-PM) evaluates the individual contributions of thrombin, fibrinogen and platelets to clot formation, and may elucidate some of the pathomechanisms of the haemostatic alterations described in this disease. This study investigated potential differences in TEG-PM variables in dogs with complicated B. rossi infection compared to healthy controls, and whether these variables correlated with indices of platelet activation. The maximum amplitude (MA) following thrombin generation (MAThrombin) was determined using kaolin-activated TEG. TEG-PM variables included MA following addition of platelet agonists arachidonic acid (MAAA) and adenosine diphosphate (MAADP), and MA due to fibrin alone (MAFibrin). In addition, platelet indices and fibrinogen concentration were determined.
Thirteen dogs with complicated B. rossi infection and five healthy controls were included. The median MAFibrin and fibrinogen concentration were significantly higher (P < 0.01 for both) and platelet count significantly lower (P < 0.01) in the babesiosis group compared to controls. No significant differences were found for MAThrombin and MAAA/ADP. MAFibrin was positively correlated with fibrinogen concentration (rs = 0.735), mean platelet volume (rs = 0.517) and mean platelet mass (rs = 0.498), and negatively correlated with haematocrit (rs = –0.685), platelet count (rs = –0.476) and plateletcrit (rs = –0.479) (P < 0.05 for all). This study suggests that hyperfibrinogenaemia offsets the severe thrombocytopenia associated with B. rossi to result in normal thromboelastograms and lack of overt clinical bleeding.
Keywords: Babesia rossi, thromboelastographic platelet mapping, thrombocytopenia, hyperfibrinogenaemia, MAFibrin
