Biomarkers in an attempt to determine prothrombotic condition alterations, for the vast majority by use of D-dimer, has long been elucidated retrospectively. D-dimer, a well known breakdown/degradation product of cross-linked fibrin, has been the subject of several researches. On the other hand to the present authors knowledge, to those of different stages of Canine Monocytic Erlichiosis (CME), D-dimer levels have not been analyzed, which should thoroughly effect therapeutic scenario. The aim of this study was to measure D-dimer concentrations and assess their value in the diagnosis of CME. Therefore D-dimer analyses by use of Wondfo Finecare Fluorescent Immunoassay were performed in four groups of dogs; (i) 8 dogs with acute CME, ii) 9 dogs with active CME infection, iii) exposured dogs (n=8) then were compared to those of healthy dogs (n=9 dogs as iv) control group. The D-dimer range in clinically healthy dogs was <0.1 mg/L. In the present study D-dimer levels were detected as follows: 0,06 +/- 0,10, 3,20 +/- 3,05, 4,04 +/- 3,94 and 0,06 +/- 0,07 mg/dl for control, acute infected, active infected and exposured dogs with a statistical significance (p<0.01) as shown in table In both infected groups, D-dimer levels increased with clinical evidence of disease. D-dimer concentration may be considered as an indicator for disease activity during acute/active disease condition and may be useful as a potential biochemical marker.