Relationship between assays of inflammation and coagulation: a novel interpretation of the canine activated clotting time.

The processes of inflammation and coagulation are known to be interconnected through several mechanisms; however, the influence of inflammation on the interpretation of coagulation assays remains unknown. Blood was collected from 87 dogs admitted to a tertiary referral intensive care unit (ICU) and 15 control dogs. The association between 2 markers of inflammation [mature neutrophil count and C-reactive protein (CRP)] and 5 coagulation parameters [activated clotting time (ACT), prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin (AT), and platelet count (plt)] were evaluated through correlation analysis. The study population was then divided into 4 groups based on severity of ACT prolongation with comparisons to all other variables assessed through an analysis of variance (ANOVA) test. A strong correlation for a biological system was demonstrated between ACT and CRP (r = 0.66; P < 0.0001). Statistically significant results were also found between aPTT and AT with the markers of inflammation, but the correlations were weaker. Within ACT groups of increasing severity, higher CRP concentrations (P < 0.0001) and lower AT activities (P < 0.0001) were identified. This study provides evidence for an association between assays of inflammation and coagulation and suggests that modification of our traditional interpretations of coagulation assays may be required. As a point-of-care test, ACT is a simple and inexpensive tool that can be used to assess an underlying inflammatory or hemostatic process.