CHRONIC DILATATION OF THE STOMACH 155 



stomach, which is very commonly produced by food masses 

 remaining in the stomach for a long period, producing press- 

 ure on the walls of the stomach leading to a lack of tone 

 in the muscular wall. This allows further accumulation of 

 fluids and gases from the fermentation of the food contained 

 and consequently the stomach becomes dilated. In some 

 individual animals the walls of the stomach are relatively 

 weak, and after eating, the food will remain in the stomach 

 for too long a period, and gradually produce a chronic dila- 

 tation. Many of the causes enumerated under acute dilata- 

 tion, if continued for some time, will result in the chronic 

 condition. 



Stenosis of the pylorus is one of the most frequent causes 

 of this condition. The etiological factors producing the 

 stenosis are the following: Spasm, gastric ulcer, erosions 

 of the mucous membranes resulting in cicatrix formation. 

 Foreign bodies which may remain in the stomach for a 

 long period, and produce by their constant irritation hyper- 

 trophy of the mucosa of the pylorus, resulting in a nar- 

 rowing or complete closing of the pyloric opening. Tumors, 

 either malignant or benign, extending into the pylorus. 

 Tumors, outside of the stomach (carcinomas, sarcomas) 

 and associated with adjacent organs or tissues. These by 

 producing pressure upon the duodenum will narrow the 

 lumen and result in a stenosis. Inflammation in organs 

 adjacent to the stomach as the liver and pancreas; or omental 

 adhesions which occur commonly after abdominal opera- 

 tions, or by being injured, as blows to the abdomen or being 

 run over by vehicles. The stenosis which is produced by 

 the above causes will interfere with the passage of the food 

 from the stomach where it remains too long eventually 

 leading to chronic dilatation. In old dogs it frequently 

 results from chronic obstipation. Further, debilitating dis- 

 eases will often produce it by interfering with the nervous 

 control of the stomach. 



Pathology.— The stomach is much enlarged and in many 

 cases distorted. When due to stenosis or obstruction to the 

 pylorus, the stomach walls are greatly thickened. The mus- 

 culature is hypertrophic and the mucous membrane is often 



