A MAJOR difficulty in the interpretation of experiments in shock is the variation of response from one animal species to another. In particular, the terminal mechanisms which lead to death appear to differ when one compares the human with the intact laboratory animal. There is no doubt as to the universal dependence of vertebrates upon the delivery of oxygen and metabolic substrates to the membranes of the individual cells via the circulation of the blood. There is no doubt that a prolonged deficiency of capillary circulation results in reversion to an anaerobic metabolic state and a gradual loss of tissue viability. It is in the course of this progression toward sequential organ failure that the major species differences between the dog, the rat, and man became more clearly demarcated.
Dogs submitted to the usual hemorrhagic shock procedures by the techniques of Fine or Wiggers are brought to a standard stage