Sequential development of esophagogastric ulcers induced in swine by infections with Ascaris suum goeze, 1782

Twenty-five experimental and five control hysterectomy derived pigs were raised colostrum free under specific pathogen-free conditions. The experimental pigs were first inoculated with A. suum eggs at 8 weeks of age, and a second dose of infective eggs was given 15 days later. They were necropsied from 4 to 10 days post second infection.The ulcers found in the stomach of these pigs were confined to the esophagogastric area. A sequence of epithelial changes, erosions, and ulceration was seen in the stratified squamous epithelium. Edema and hemorrhage were noted in the lamina propria and submucosa. Vascular changes in the area were characterized by thickening of the wall and presence of thrombi in arteries as well as cellular degeneration and vacuolization of the media and intima of the veins.Changes in the muscularis were characterized by edema and degeneration of the muscle cells, which later were replaced by fibroblasts and heavy infiltration by eosinophils.Three of the control pigs received one dose of A. suum eggs, and were killed one on each of the 8th, 9th, and 10th days post infection. The remaining two pigs received no infective material and were killed when they were 11 weeks of age. Neither the uninoculated pigs nor the once-inoculated animals developed ulcerations in their stomachs.The possible mechanisms by which esophagogastric lesions are produced following A. suum larval migrations are discussed.