Activity of fibrinolytic and coagulation pathway in babesiosis of dogs

The purpose of this study was to measure markers of fibrinolytic and coagulation activity (D-dimer and thrombin-antithrombin complexes-TAT) and inhibitor activity (antithrombin III -AT III) in dogs with babesiosis. It was hypothesized that these markers could be used to demonstrate that coagulation and fibrinolysis are activated in dogs with babesiosis. The plasma levels of D-dimer, TAT concentration, AT III activity, PLT and RBC number were measured in 30 patients with babesiosis. The Babesia canis canis subspecies was confirmed using PCR methods. The D-dimer level was assessed using citrated plasma and the Tina-quant immunoturbidimetric assay (Roche Diagnostic, Indianapolis, Indiana) on a automated biochemistry analyzer (Olympus AU 600, Olympus Diagnostica GMBH, Hamburg, Germany). The AT III analyses were performed in citrated plasma at automatic coagulometer IL 9000 (Instrumentation Laboratory, Milano, Italy), using reagents of Dade Behring (Marburg Gmbh, Marburg, Germany). TAT concentration was measured in citrated plasma using Enzygnost TAT micro kit (Dade Behring Marburg GmbH, Germany) and microplate reader Dynex Technology MRX (Chantilly, USA). PLT and RBC were performed in whole blood using a automatic analyser Serono 9120 (Baker Diagnostic, USA). The control group consisted of 30 clinically normal dogs of different sex, breeds and age distribution. Mann-Whitney U test were used for statistical analysis, at p<0, 05 significance level (*). The plasma levels of D-dimer were not changed during babesiosis. However, concentrations of TAT complexes were significantly increased, followed by decreasing of AT III activity. Number of RBC and PLT were significantly decreased, compared with healthy dogs. Conversion of prothrombin into active thrombin is a key event within the coagulation cascade. Thrombin is inhibited by antithrombin III - this results in an inactive proteinase-inhibitor complex: TAT. The fine balance of the homeostatic mechanisms is moved to the side of thrombine and fibrine production due to lower activity of AT III in babesiosis of dogs. Demonstrated high concentration of TAT complexes in patients with babesiosis confirm the hypercoagulable state. Marked thrombocytopenia was present in all dogs with babesiosis, since anemia was not allways present, but was statistically significant. This results indicated that babesiosis is an unlikely diagnosis in the absence of thrombocytopenia. Procoagulant influence can be the result of the release of ADP and phospholipides of cellular membrane after lysis of erithrocytes. D-dimer is the neoantigen formed as a result of plasmin digestion of cross-linked fibrin. In canine medicine, the use of D-dimer is relatively new. Concentrations of D-dimer were not changed, indicating that endogenous fibrinolytic activity remain unaltered during babesiosis. This finding excluded disseminated intravascular coagulation as a possible cause of thrombocytopenia and AT III decrease. In a clinical setting, markers such D-dimers and TAT complexes would be useful in identifying animals with activated coagulation and fibrinolysis. Naturally occuring canine babesiosis thus represents a potentially hypercoagulable state and may serve as a valuable model in the study of certain components of other hemolitic diseases.