Pathogenesis. 389 



(gravid uterus, filled rumen, enlarged ovary, enlarged pros- 

 tata) ; a spleen enlarged in consequence of hemorrhage may not 

 infrequently cause stenosis of the bowels. Hendrickx saw in a 

 horse a compression of the intestines due to a detached, partly 

 ossified cryptorchitic testicle, which subsequently broke through 

 the atrophic intestinal wall into its lumen. 



Intestinal stenosis may also be caused by internal herniae 

 before they become strangulated; the clinical picture then usual- 

 ly terminates by the symptoms of complete incarceration. Para- 

 sites (ascaris, gastrophilus larvae [Kater, Rexilius],_ intertwined 

 ta?nife) will only exceptionally produce a picture similar to in- 

 testinal stenosis. 



Pathogenesis. According to the character of the enumer- 

 ated causative factors, the intestinal lumen usually becomes 

 narrowed very gradually; in exceptional cases the stenosis re- 

 mains stationary or it only occurs temporarily (diverticulum, 

 internal hernia, compression caused by an overfilled rumen). 

 The narrower the affected portion of the intestine, even under 

 normal conditions, the firmer the feces, the more abundant and 

 the drier the ingested feed has been, the earlier, the oftener, 

 and the longer will the passage of feces through the con- 

 stricted portion be interfered with. The fecal masses accumu- 

 lating in front of the narrowed point stimulate the intestines to 

 forcible contractions at the place where the accumulation has 

 taken place; some of these are convulsive and cause colicky 

 pains. These forcible contractions will finally succeed in press- 

 ing the accumulated feces through the stenosed portion and the 

 time which elapses before this occurs depends upon the degree 

 of stenosis and upon the consistency of the feces. After the 

 feces have passed the narrowed point, the convulsive contrac- 

 tions and the pains cease. Hypertrophy of the forcibly contract- 

 ing muscularis and dilatation of the intestine will develop in the 

 course of time. The nearer to the stomach the constriction is 

 situated, the sooner after the ingestion of food will abdominal 

 pains come on, and a chronic dilatation of the stomach will 

 usually develop; such a condition may, however, also develop 

 in stenosis of the large intestine. In the latter condition attacks 

 of pain occur independently of the ingestion of food ; in stenosis 

 of the rectum they commonly come on before defecation. Those 

 portions of the intestines which are situated between the stric- 

 ture and the anus do not contain a great deal of feces, hence 

 they act sluggishly. The feces accumulate and decompose in 

 front of the stricture and frequently become instrumental in 

 producing chronic intestinal catarrh, which influemes the nutri- 

 tion of the animals unfavorably. The stenosis may finally lead 

 to complete occlusion of the bowels. 



Symptoms. In the horse and in cattle a clinical picture is 

 observed at variable intervals, which is identical with that met 

 with in impaction (see pages 367 and 376) ; the attacks may last 



