Atrophy of the mucous membrane of the intestine is an occasional consequence of inflammations, catarrhal, dysenteric, and other. There have also been described atrophic and degenerative changes in the intestinal nerves in acute fevers and in acute affections of the central nervous system. The changes in the nerves are accompanied by changes in the muscle.
Amyloid degeneration is the most frequent retrograde change in the intestine. It affects the arteries and capillaries of the mucosa and sub mucosa, and especially the vessels of the villi, but it often extends to the whole tissue of the villi except the epithelium, and to the muscular bundles of the submucosa. To the naked eye the intestine frequently appears pale and smooth, but the condition is best detected by the addition of iodine solution. The affected villi then appear as deeply stained granules, while the closed follicles and Peyer's patches are unaffected. If ulcers be present, as is not infrequently the case, they also are unaffected and show a contrast in colour. The villi are frequently extensively lost in amyloid disease, but this may be a postmortem effect, the brittle amyloid structures being broken off in handling the intestine.
Necrosis, which here sometimes assumes the characters of Gangrene, occurs, as mentioned above, in various conditions, infarction, dysentery, hernia. It also results occasionally from continued pressure by hard contents. This is most common in the vermiform appendage, but also occurs in the colon and rectum from hard faeces. The result is the formation of ulcers. Gangrene may also result from traumatic separation of the mesentery, when this occurs close to the intestine.
These •mostly consist of the ordinary contents dried-in and impregnated with lime salts. The concretions have a kernel composed usually of dried faeces, but sometimes a gall-stone, a fruit-seed, or a mass of hairs, forms the kernel. The central parts so formed are coated with phosphate and carbonate of lime. Concretions are very common in animals, especially in the horse, in which they have been found weighing 20 pounds. They are composed of the husks of corn mixed with hairs which the animals have licked from their bodies and swallowed. These are felted together and compacted into large balls.
Gall-stones also occur as foreign bodies in the intestine, and sometimes they are large enough to cause obstruction at the ileo-caecal valve or elsewhere.
Vegetable parasites are of little consequence if we except those considered in previous paragraphs.
Nothnagel, I.e.; Scheimpflug, Zeitschr. f. klin. Med., ix., 1885; Furneaux-Jordan, (Fatty change and failure of muscular wall as cause of obstruction) Brit. Med. Jour., 1879, i., 621; Wagner, Arch. d. Heilk., 1861; Kyher, (Amyloid) Virch. Arch., lxxxi., 1880; Edinger, (Amyloid dis. and dilat. of colon) D. Arch. f. klin. Med., 1881; Zesas, (Separation of mesentery) Arch. f. klin. Chir., 1886; Schuberg, (Concretions) Virch. Arch.,xc, 1882; Laboulbene, Arch. gen. de med., xxii., 1873; Friedberger und Frohner, Lehrb. d. path. d. Hausthiere, 1885; Leube, in Ziemssen's Cyclop., vii., 1877.