The impact of systemic inflammatory response syndrome (SIRS) on all phases of coagulation is largely unknown in dogs.Fifty-six healthy dogs (controls) and 25 diseased dogs were included. Based on physical and hematological examination, dogs were classified as “no-SIRS” (n=7) or “SIRS” (n=18). Evaluated coagulation variables included platelets, coagulation times, fibrinogen, antithrombin (AT), FVIII, protein C, protein S, activated protein C (APC)-ratio, calculated from aPTT with and without presence of APC, and kaolin-activated thrombelastography (TEG).Overall, no-SIRS and SIRS were characterized by hypocoaguable state (P<0.001 compared to controls) i.e., prolonged coagulation times, decreased AT (median 59U/L and 89U/L versus 126U/L), and FVIII (median 19U/L and 70U/L versus 102U/L). In no-SIRS and SIRS, APC-ratio was significantly lower than in the controls (median 1.1 and 2.0 versus 2.5, P<0.01, P<0.001).Severe coagulopathies may be present in critically ill dogs without concurrent SIRS. APC-resistance is a frequent finding in severely diseased dogs.