A standard experimental preparation has been developed for the study of acute experimental hemorrhage, based on the principle of bleeding a certain percentage of the predetermined blood volume of the animal. Previous work from this laboratory has shown that by bleeding a definite percentage of the measured blood volume of the experimental animal, the mortality rate could be predicted with an accuracy ranging within ±5%.1
Further work along these lines, however, revealed a conspicuous, constant, and significant difference in mortality rates between groups of dogs subjected to acute hemorrhage under strictly the same and standard experimental conditions, but at different seasons of the year. The possibility of a seasonal variation in the tolerance of dogs to acute hemorrhage was suspected, and this suspicion stimulated the development of this study.
Material and Method
Throughout 1960-1961, a total of 112 adult mongrel dogs were subjected to acute experimental hemorrhage at different