Intestinal catarrh may be acute or chronic and effect a small or large portion of the small intestines or the colon. Acute intestinal catarrh is almost always attended by diarrhea, is due to the same causes, and requires the same treatment.

Chronic catarrh of the bowels is a serious disease, all the more so because it is seldom recognized and treated before considerable time has elapsed and the consequences have become very marked.

Catarrh of the small intestines is probably far more common than it is usually supposed to be. It is a cause and a consequence of intestinal dyspepsia and auto-intoxication. It results from long-continued irritation of the mucous membrane by improper food, from defects of the nervous system causing a disturbance of the digestive processes, from continued irritation by the products of fermentation and putrefaction, from the direct action of bacteria on the mucous membrane, from portal stasis or abdominal plethora resulting either from intestinal causes, hepatic congestion, or diseases of the heart. There are, therefore, a large number of causes of catarrh of the small bowels. Two types of cases may be given as illustrating the disease.

(a) Young people, chiefly young women who are afflicted by constipation and intestinal dyspepsia. They suffer from cold hands and feet with occasional burning of the same, gastric indigestion from slight causes, and nervous symptoms. The evidences of catarrh are indistinct. There may be excessive secretion of succus entericus and peristaltic movements, causing loud gurgling and rumbling in the abdomen owing to the mixture of gases and fluids; nevertheless, the patient may be constipated because time is given for the absorption of fluids in the lower bowel; in fact, constipation is the rule. In a few cases the movements of the bowels are accelerated to such an extent as to cause diarrhea, in which event the faeces may contain undigested food (lienteric diarrhea) or mucus, and sometimes blood. The presence of an excess of mucus in the bowels hinders absorption of the food, and the patient becomes pale, thin, and debilitated owing to intestinal insufficiency. The flatulence and disturbance of nutrition may be great, the nervous symptoms meanwhile increasing until the patient becomes distinctly neurotic and unfit for active physical or mental work.

(6) The second type is that which occurs in middle-aged or elderly persons. It is usually the result of abdominal plethora and failure of the liver (hepatic insufficiency). It occurs in men as well as women, but especially in the latter. They have got to the age when the preservation of a good figure is of no moment. They find it convenient to loosen their corsets; moreover, it is necessary for them to do so on account of increasing rotundity. They usually have a florid complexion and some excess of fat. They suffer from palpitation and shortness of breath on exertion and frequent attacks of indigestion. Owing to intestinal indigestion their liver is flooded with toxins absorbed from the bowels, and it is unable to deal with all the products of imperfect digestion or bacterial decomposition. Consequently the liver becomes congested, enlarged somewhat, and dams up the blood in the portal veins and the branches from the stomach and bowels. These veins lose their elasticity and gradually become dilated; like varicose veins in the leg, they are always overfull. These overfull veins in turn cause congestion of the veins and capillaries (passive hyperaemia) of the intestinal mucous membrane. The consequence is blood stasis, which acts prejudicially to the mucous membrane in various ways: (a) The intestinal walls do not get sufficient oxygen; (6) in consequence of this the muscles of the intestines, and especially of the villi (those numerous tiny little pumps), become weakened; (c) failure of muscular power in the intestines means a delay in absorption of the digested food; (d) moreover, the intestinal stasis favours bacterial decomposition and toxaemia. As the congested liver is unable to destroy all the toxins brought to it, some of these poisons escape into the general circulation. They find their way into the pulmonary circulation and set up recurrent bronchitis. In time the heart becomes badly nourished, its muscles feeble, its ventricles dilated, and cardiac weakness with a low-tension pulse is added to congestive bronchitis, toxaemia, and increasing bodily debility.

In these cases of catarrh of the small intestines there may be: (a) no diarrhea, a soft pultaceous motion being discharged daily; (b) constipation may alternate with diarrhea in which the stools are soft and contain mucus; or (c) there may be continuous diarrhea, the faeces often being acid, the contents of the small intestines being hurried along to the rectum and discharged with a rapid movement.