Physiologic correlates dependent upon mode of death

Abstract

Some of the physiologic changes that occur in small mammals and that are dependent upon mode of death have been evaluated in an investigation with 180 rats. Nine different methods of sacrifice (ether inhalation, chloroform inhalation, intraperitoneal ether, intraperitoneal chloroform, intraperitoneal sodium pentobarbital, decapitation, concussion intracranial ethanol, and cervical dislocation) have been comparatively studied. The differential dependency upon these modes of death of organ weight and appearance, and of the time required for cessation of heart beat, cessation of respiration, loss of righting reflex, and duration of neuromuscular convulsion has been determined. The terminal method of intracranial injection of ethanol is demonstrably the best method of sacrifice in view of (1) the instantaneous blockage of respiration, (2) the very brief period of neuromuscular convulsion, (3) the lack of significant hemorrhage, (4) the usual immediate cessation of heart beat, (5) the convenience of the method, and (6) the lack of circulatory responses characterized by changes in organ weights. This method should be avoided, as well as decapitation, cervical dislocation, and concussion, when pulmonary tissue is to be extracted from animals because of the capillary rupture of the lungs following these methods. Two commonly employed methods of sacrifice, chloroform anesthesia and concussion, have been found less suitable than other methods. Concussion is to be particularly avoided since it results in relatively long periods of neuromuscular convulsion, respiration, and cardiac beating, and is further complicated by significant gross hemorrhage, traumatic interpulmonary hemorrhage, and related losses of weight in liver and other organs.