Etiology. Pathogenesis. 365 



of obstipation in horses, because feed of this type has to be 

 taken in very much larger amounts than more nutritious food 

 and it furnishes feces of much denser consistency, which are 

 more difficult to move along. Sucli food stuffs are straw, par- 

 ticularly if cut into short chaff, or if it is taken up from the 

 bedding straw (socalled straw feeders), corn stalks, hard-fibrous 

 clover, alfalfa, etc. Constipation is, on the other hand, fre- 

 quently produced by feeding materials rich in the salts of the 

 earthy metals such as bran, crushed corn and barley, marshy 

 hay, and also upon the ingestion of sand. All the aliove men- 

 tioned food stuffs act particularly unfavorably in sudden change 

 of feed and with insufficient exercise. 



Retarded movement of the large intestines may cause obsti- 

 pation of the gut, even on proper feeding. This is seen in old, 

 enfeebled horses, in fat animals which do not exercise much, 

 usually also in horses of a listless temper. Insufficient peristal- 

 tic motion may also be consecutive to chronic intestinal catarrh, 

 and the latter may have developed upon a thrombotic or embolic 

 basis. 



The cause of the disease is sometimes a disturbance of mas- 

 tication (bad teeth), liecause then the feed is not sufficiently 

 broken up before it gets into the gastro-intestinal tract. Insuffi- 

 cient peristalsis and frequent anomalies of teeth in old horses 

 explain the frequency of obstipation in advanced years. 



The combined use of morphine and atropine against shoulder lameness causes 

 many cases of obstipation with subsequent bloating or rupture of the stomach, be- 

 cause atropine diminishes the intestinal secretion and morphine suppresses peri- 

 stalsis. 



Secondary obstipation is seen after intestinal stenosis, after 

 intestinal o])turation existing for some time, in combined paraly- 

 sis of the tail and sphincter, and exceptionally following throm- 

 bo-embolic processes of intestinal vessels if these have lasted at 

 least for several days. 



Pathogenesis. Retardation of peristalsis and a firmer con- 

 sistency of the intestinal contents bring about, even under nor- 

 mal circumstances, a gradual accumulation of feces, particular- 

 ly in the narrower portions of the intestines, where the removal 

 of the contents is slow, even under physiologic conditions. An 

 accumulation of feces occurs most frequently in the stomach- 

 like dilatation of the colon, in front of the first portion of the 

 small colon and it may spread from here to other portions of 

 the colon and even to the cecum. Sometimes obstipation de- 

 velops in the pelvic flexure and at other times again in the cecum 

 in front of the comparatively narrow opening of the colon ; also 

 fairly frequently in front of the ileo-cecal valve, rarely, how- 

 ever, exclusively in the rectum, in the region of the second 

 flexure of the duodenum and only exceptionally in the jejunum. 



The accumulation takes place in either one of two modes. 

 The above mentioned portions of the small intestines, most fre- 



