126 ANIMAL CASTEATION 



oi' tho cord. In the nonnal subject the lumen of the 

 eoi-d is not sutticiently large to permit of hernia. Des- 

 iccation and cicatrization of the stump of the cord 

 completes the process of normal spontaneous healing 

 of the navel. 



In umbilical hernia the margins of the opening in 

 the abdominal wall is usually somewhat thickened, and 

 in some cases the margin of the peritoneum is firmly 

 adherent to the margin of the abdominal opening. In 

 cases that have heen unsuccessfully treated, where 

 clamps or skewers have been employed, eonsiderabls 

 hypeitrophy of all tissue surrounding the opening in 

 the abdominal muscles exists. In addition to this 

 there is present more or less fibrous or cicatricial 

 tissue, which renders permanent closure of the abdom- 

 inal opening difficult in some cases. 



Symptoms of umbilical hernia are the presence of 

 fluctuating swelling at the navel, which is usually suffi- 

 ciently free from adhesions that reduction is easily 

 effected and the margins of the opening are readily 

 outlined by palpation. This may be done by retuniing 

 the contents of the pouched mass into the peritoneal 

 cavity while the colt is in a standing position. When 

 a subject is placed in dorsal recumbency, spontaneous 

 reduction of umbilical herjiia usually occurs, but im- 

 mediately intra-abdominal pressure is increased by re- 

 sistance of confinement or straining, the hernial pouch 

 is at once filled with intestine or omentum and it so 

 remains until relaxation of the abdominal muscles and 

 diaphragm occurs. 



Umbilical hernia is distinguished from abscess in 

 that abscess remains confined within the l)ounds of its 

 walls regardless of position assumed by the subject, 

 is therefore not reducible and has no patent communi- 



