The Abdomen 179 



cecal valve, owing to the weight of the water exerting too strong 

 lateral pressure for the intestine safely to bear. While this may be 

 true as regards the cat it does not hold good for the dog. In the 

 latter animal the valve is nearly always patent and fluids can be 

 forced up as far as the stomach without any risk of damaging the 

 bowel wall. 



In one of Senn's cases of artificial invagination of the ileum 

 into the colon the abdomen was reopened on the third day and the 

 neck of the intussuscipiens exposed so as to observe the mechanism 

 of disinvagination by rectal injections of water. As soon as the 

 colon was well distended the adhesions at the neck of the intus- 

 suscipiens began to give way and complete reduction followed. The 

 animal recovered. 



III. Constriction. Under this heading are included all 

 obstructions arising by causes developing in connection with the wall 

 itself, namely, all forms of neoplasms, strictures, and cicatrices. 



Tumors of the intestinal canal proper are rare. Adeno-carci- 

 noma and sarcoma have been observed. Organic strictures are of 

 somewhat more common occurrence and offer an admirable field 

 for surgery. Unlike cancerous tumors they are not productive of 

 cachexia and are lethal only to the extent that they lead to starva- 

 tion by occluding the tract, or to autointoxication. ' The duodenum 

 is a favorite seat for the development of stricture but it has also 

 been found in the colon. Cicatricial strictures may result from 

 healed ulcers and may follow coalescence of the resected bowel after 

 end-to-end anastomosis. The rectum occasionally becomes occluded 

 in puppies suffering from chronic diarrhea, the epithelial lining de- 

 generating and adhesion taking place between the submucosa layers. 

 According to Cadeac, lipomata may develop in the submucosa and 

 cause projection of the mucosa. 



The mesenteric lymphatics are also occasionally affected with 

 growths, such as lymphadenomata, lympho-sarcomata, and tu- 

 bercles. 



Obstruction is sometimes seen in puppies owing to congenital 

 occlusion of the canal, generally in the region of the anus. This 

 condition will be referred to under The Rectum and Anus. 



Symptoms and Diagnosis. These vary according to the charac- 

 ter and position of the growth. Malignant tumors have a pro- 

 found effect on the entire organism, often of extreme and fatal 



