Canine shock: irreversibility and coagulopathy.

Canine shock was experimentally induced by "superior mesenteric artery (SMA) occlusion followed by release:" two hours of occlusion produced reversible shock while four hours of occlusion caused irreversible shock. In both situations, the animals showed coagulopathy but the magnitude of same was more severe in animals with irreversible shock. The nature of coagulation changes was suggestive of intravascular coagulation. Histological changes showed widespread intravascular fibrin thrombi in the liver and the kidney in animals with irreversible shock and only limited local intravascular coagulation in the subcapsular region of the liver in those with reversible shock. The importance of diffuse intravascular coagulation in the irreversibility of shock was also corroborated by the "reversion" of shock by prior heparinization.