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 cæcum formed herniæ 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 dependent 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 extensive extravasations. The inflamed membrane may soften, become friable and tear more extensively, or if the patient survives, the exudation becomes organized, thickening and strengthening the margins of the wound and causing them to contract so as to strangle the enclosed loop of intestine.
Symptoms. The indications are those of intestinal obstruction, to which accordingly the reader is referred. The only possible indication of the exact nature of the lesion is to be obtained by rectal exploration. Herniæ through the meso-colon or broad uterine ligament may be reached in this way, and possibly diagnosed.
Treatment. Laparotomy alone gives any hope of success, and this will only be warranted when a certain diagnosis has been reached.
HERNIA THROUGH THE FORAMEN OF WINSLOW IN THE HORSE.
Anatomical considerations, small size and elevated position of foramen, length and freedom of mesentery of jejunum; spare diet, draught, straining, rolling, colic. Symptoms: of intestinal obstruction only, lesion found at necropsy.
The foramen of Winslow is a comparatively small opening between the lesser curvature of the stomach and the liver, and between the gullet and its cardiac ligament on the left side and the gastro-hepatic omentum on the left. With its elevated and anterior position in the abdomen it would seem to be little exposed to this kind of accident, yet a number of recorded instances in the horse, show that it is certainly not immune. The great mobility of the jejunum, owing to the extra length of its mesentery is believed to be the essential predisposing cause. A spare diet, or one which is in small bulk, allows the comparatively empty gut to pass more readily through the small opening. Severe efforts in draught and straining in defecation and parturition are also invoked as means of pressing the jejunum through the orifice. So with the concussions attendant on falls and the unwonted positions taken in decubitus and rolling on the back in wantonness or colic.
Symptoms of this lesion are essentially those of intestinal obstruction, with usually a rapid and fatal course. An accurate diagnosis is impossible during life.