THE DIGESTIVE SYSTEM 19 



attenuated, and, in rare instances, they may become so 

 weak that they are easily ruptured. 



Symptoms. The usual symptoms evidenced in an 

 animal afflicted with esophageal dilatation consist of a 

 gradually developing tumefaction or enlargement in 

 the cervical region while the animal is eating, due to the 

 accumulation of the food in the dilated portion of the 

 esophagus. The enlargement gradually subsides after 

 eating, until no enlargement is observed. 



Treatment. The treatment of esophageal dilatation 

 is of little avail, and is primarily confined to surgical 

 interference. 



Perforation 



Esophageal perforation is not very common in swine. 



Etiology. It may be the result of erosion due to 

 disease processes, such as actinomycosis, tuberculosis, or 

 necrobacillosis, resulting in a complete destruction of 

 portions of the esophageal walls and thus permitting the 

 contents of the esophagus to infiltrate into the surround- 

 ing structures. 



Perforation may also result from injury due to some 

 foreign body that has been ingested and lodged in the 

 esophagus. Weston reported the case, in The American 

 Veterinary Review (Vol. 40, p. 658), of a hog that had 

 swallowed a piece of sharp tin, which had perforated the 

 thoracic portion of the esophagus. A sinus was formed 

 in the adjacent lung, in which a small mass of food had 

 accumulated. 



Lesions. The lesions resulting from perforation of 

 the esophagus are quite variable and consist not only of 

 the destruction of the esophageal walls, but also of 

 tissue changes induced by the escape of food from the 

 esophagus in the surrounding tissues. In some instances 

 the primary lesions consist of an inflammatory edema, 

 while in other instances the primary lesions are tuber- 

 culous, actinomycotic, or necrobacillary. 



Symptoms. The symptoms resulting from eso- 

 phageal perforation vary according to the secondary 



