Definition. Causes: Concussions in horse especially, anatomical
conditions in cattle, pediculated tumors, dystokia, hernia of small
intestine in horse, ox, broad ligament, pelvic hernia. Lesions:
Congestion, hemorrhage of hernial viscus, adhesions, softening,
thickening, strangulation. Symptoms: Intestinal obstruction, rectal
exploration. Treatment: Laparotomy.
_Definition._ This consists in a protrusion through an opening,
congenital or acquired, in the double fold of peritoneum (mesentery)
which passes off from the abdominal wall to support a viscus, or that
which passes from organ to organ (omentum).
_Causes._ The lacerations of mesentery or omentum are attributed to
sudden concussions of various kinds (falls, blows, leaps, violent
efforts), and have been especially found in horses in which the bulk and
weight of the contents of the digestive organs furnish a special
predisposition. In ruminants in which the contents of the abdomen are
equally bulky and heavy the lesion is rarely seen, probably because the
great bulk of the ingesta lies in the first three stomachs, and because
the large intestines 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 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.