Hernia Through the Mesentery, Omentum, etc. 377 



lesion is rarely seen, probably because the great bulk of the 

 ingesta lies in the first three stomachs, and because the large in- 

 testines are folded up in the mesentery which supports the small, 

 thereby strengthening this means of support and restricting the 

 freedom of movement on the part of the intestines themselves. 

 In carnivora the limited bulk of the intestines and their contents, 

 and the relative shortness of the mesenteric folds largely obviate 

 the predisposition. 



Pediculated tumors of mesentery or omentum may drag on the 

 delicate membrane so as to cause laceration, and circumscribed 

 peritonitis, by producing softening and friability, may act as a 

 causative factor. Violent straining in defecation or parturition is 

 another cause of laceration. 



In solipeds the loosely suspended and eminently mobile small 

 intestine is the viscus which most commonly forms a hernia 

 through such adventitious openings, either through the great 

 mesentery, the great omentum, the gastro-splenic omentum, the 

 mesentery of the umbilical vein (falciform ligament of the liver), 

 or the gastro-hepatic omentum. Cases are on record, however, 

 in which the floating colon, the double colon and even the caecum 

 formed hernise through the peritoneal lacerations. 



In cattle the most common lesion is the hernia of a knuckle of 

 intestine through a laceration in the mesentery, but, the rupture 

 has also occurred in the great omentum and exceptionally in the 

 broad ligament of the uterus which is very extensive in these 

 animals. Pelvic hernia or gut tie as usually described is depen- 

 dent on a laceration of the mesentery of the spermatic artery. 



Lesions. The fold of intestine which makes the hernia is liable 

 to become strangled, and sometimes twisted in the opening, so 

 that the circulation of blood and ingesta is interrupted, congestions 

 and hemorrhages set in, and necrosis and general infection follow. 

 Oftentimes a fibrinous exudate is thrown out, binding together 

 the intestinal convolutions, and attaching them to the margins of 

 the mesenteric or omental opening. Similarly the lips of the 

 lacerated wound in the mesentery become covered with blood 

 clots, or congested, or infiltrated, and sometimes the seat of ex- 

 tensive extravasations. The inflamed membrane may soften, be- 

 come friable and tear more extensively, or if the patient survive, 

 the exudation becomes organized, thickening and strengthening 



