298 Acute Dilatation of the Stomach of the Horse. 



tlie stomach; a serious affection of the intestines also prevents 

 the evacuation of the stomach by reflex irritation ; besides every 

 somewhat intense increase in the size of the stomach-like dilata- 

 tion of the colon prevents mechanically the flow of the gastric 

 contents towards the small intestines, because the pylorus is 

 pressed against the stomach by the dilated and tense large intes- 

 tine. Secondary gastric dilatation occurs more easily the sooner 

 the causative affection sets in after the ingestion of food. 



Pathogenesis. The causes of acute dilatation of the stom- 

 ach bring about swelling of the food contained in the stomach. 

 The gastric contents then ferment in consequence of insufficient 

 mixing or of inherent fermentability so that more or less gas is 

 formed. The gastric mucosa is stimulated to an increased se- 

 cretion and all of these factors lead to a stretching and dilata- 

 tion of the stomach. Whether after ingestion of coarse or of 

 poorly masticated food a tonic contraction of the pylorus occurs 

 by reflex irritation has not been proven, but neither has 

 its occurrence been excluded. The rapidly developing ten- 

 sion of the gastric wall and the irritation of the mu- 

 cosa by the decomposition products of feed mash pro- 

 duce convulsive contractions of the gastric muscularis ; 

 these cause colicky pains, which are quite intense since 

 the contractions are severe, recur frequently and last a 

 long time. They are, however, not intensified by a sudden in- 

 crease of intraabdominal pressure as in throwing down or roll- 

 ing. The drier the contents of the stomach, the less gases or 

 irritating decomposition products are formed and the less ener- 

 getic are the contractions of the stomach; these muscular con- 

 tractions may not appear at all after the ingestion of cold water, 

 which acts as a paralyzant to the muscularis. The stomach 

 pushes the diaphragm forward proportionately to its size, mak- 

 ing respiration more difficult; however, in consequence of the 

 diminution in the intra-thoracic negative pressure and on ac- 

 count of the mechanical effect against the diastole of the heart, 

 this organ receives less venous blood, and the heart beat usually 

 becomes more rapid. In dilatation of a high degree the internal 

 tension can become so great that the wall of the stomach rup- 

 tures. Considerable losses of substance of the gastric wall 

 (caused by the presence of gastrophilus larvae, gastric ulcers) 

 predispose to this accident. However, rupture is probably more 

 frequently due to a sudden increase in the intraabdominal pres- 

 sure, as it occurs in throwing do^\^i, in reckless rolling and vom- 

 iting. It can also well be imagined that occasionally rupture 

 may occur in consequence of violent contractions of the gastric 

 muscularis with an intense increase of intragastric pressure. 



DasRonville and Brocq-Roiisseau experimented on the normal stomach of dead 

 horses and found that the introduction of 26-40 liters of air or of 10-17 liters of 

 water were sufficient to cause rupture of the gastric wall ; a manometer connected 

 with the pylorus showed a pressure of 5 cm. mercury only. Fayet and Gattend 



