86 SWINE PRACTICE 



resulted from the influences of some substance upon the deglutition 

 centers of the medulla. 



TUMORS 



Pharyngeal tumors in swine are not very common. Occasionally 

 polypoid fibromas are observed, but they are rare. Of the malignant 

 tumors the epitheliomas are most often met with; however, these 

 are rare. Adenomas and carcinomas also have been observed, but 

 infrequently. 



Esophagus 



JI ALFOR M ATIONS 



Malformations of the esophagus are rather rare. The canal may 

 end abruptly at the lower end of' the upper third, beginning lower 

 down, and continue to the stomach, or the esophagus may form a 

 union with the trachea. In rare instances fistulous openings have 

 been observed in the cervical region. 



STENOSIS 



Steiiosis, or narrowing of the esophagus, is not infrequent. This 

 condition occurs most frequently at the pharyngo-esophageal junc- 

 tion or at the cardiac termination, the cause being either extrinsic 

 or intrinsic. 



Etiology. — Among extrinsic causes may be pressure from enlarged 

 thyroids, tumors, aneurysms, or abscesses. Foreign bodies, too, often 

 produce partial obstruction of the esophagus, thus causing a tem- 

 porary stenosis. The intrinsic causes are more frequently due to 

 scars or scar tissues that have formed as a result of injuries or of 

 diseased processes of the esophageal tissues. Hyperplasia of the 

 esophageal muscle, also, may produce stenosis. 



Lesions. — The usual anatomical changes observed in esophageal 

 stenosis consist of cicatrized fibrous tissue. The extent of the trouble 

 varies, but as a rule it involves only a small portion of the esophagus. 

 The stenosis may form a regular or irregular diminished lumen. 



Symptoms. — The symptoms evidenced in esophageal stenosis con- 

 sist of difficult deglutition and sometimes dilatation (which see), 

 succeeded by the formation of jabot, which may be observed in ani- 

 mals thin in flesh. 



Treatment.— Surgical interference, which may or may not be sue- 



