Influence of diet on experimental swine dysentery. 3. Pathological changes.

Three experiments have been carried out to elucidate the possible influence of the vitamin E and selenium content of the feed on experimental swine dysentery. In most of the pigs given a vitamin E and selenium deficient diet, large and diffuse pseudomembranes appeared in the spiral colon, which also usually displayed a distended appearance and prominent oedematous infiltrations in the mesentery. The histological examination revealed large fibrinous pseudomembranes attached to defects on the mucosal surface. There were also pseudo-membranes containing necrotic mucosal tissue. Fibrinoid thrombi within minute vessels were readily observed in the latter lesions. The vitamin E supplemented pigs had colonic lesions very much like the deficient animals, while half of the selenium supplemented animals developed none or moderate inflammatory changes, the other half displayed, however, prominent pseudomeinbranes in the colon. Ten out of 26 pigs supplemented with both vitamin E and selenium were not affected by swine dysentery. In the remaining pigs catarrhal inflammatory lesions dominated in the colonic mucosa. In some of these animals pseudomembranes occurred, but they were usually small and of limited distribution. The vascular thromboses and tissue necrosis demonstrated within the colonic lesions are found to be compatible with a Shwartzman reaction. Erythrocytic “thrombi” and other phenomena associated with stasis are further believed to be of pathogenetic importance in this respect. It is emphasized that this report also illustrates the enhancing effect of a combined supplement of vitamin E and selenium on resistance to swine dysentery.