Abstract
Birth asphyxia is believed to be related to early pathological changes in the structure of the digestive tract. The purpose of the present study was to evaluate morphological changes in the digestive tract following asphyxia, and to clarify the pathogenesis of neonatal necrotizing enterocolitis and gastric rupture. Asphyxic stress was induced by a 3-minute clamping of the airway of intubated formula-fed puppies. Each pup was necropsied 1 or 4 days after an asphyxic episode, and the digestive tract was evaluated pathologically. Gross observations revealed various degress of congestion, edema, and/or erosion in 15 out of 43 (35%) puppies with asphyxic stress. Histopathologically, the characteristic lesions of the affected intestinal walls included separation, perforation, sloughing of villous epithelials, capillary dilation, cell infiltration, edema, and hemorrhage of the mucosal and submucosal layers. The degree of damage was graded from 0 to 5. All pathological changes by gross observation were greater than grade 3, while controls were less grade 2. Noteworthy was focal hemorrhage in the gastric wall in one pup. Histologically, the hemorrhage was located in the submucosal layers, in areas where there no muscle fibers. This hemorrhaging is cogent evidence to support the suggestion that in the etiology of neonatal gastric rupture, this area becomes the weakest point of the gastric wall under increased intra-gastric pressure. These results also strongly suggest that birth asphyxia may be a major factor in neonatal necrotizing enterocolitis as well as in neonatal gastric rupture.
