Definition. Seat: ileum into cæcum, rectum through sphincter, duodenum
into stomach, floating small intestine into itself, cæcum into colon.
Lesions: blocking, or tearing of mesentery, dark congestion,
peritoneal adhesions, incarcerate gut, necroses, sloughing of
invagination. Symptoms: colics of obstruction, enteritis, and septic
infection, eructation, emesis, tenesmus, signs of sepsis and collapse,
death in seven hours or more, or recovery by disinvagination or
sloughing. Diagnosis: by rectal exploration or passing of slough.
Treatment: oily laxatives, demulcents, enemata, mechanical restoration
of everted rectum, laparotomy.
_Definition._ The sliding of one portion of an intestine into a more
dilated one, as if a few inches of the leg of a stocking were drawn
within an adjoining portion which is continuous with it.
_Seat._ It is most commonly seen in the inversion of the small intestine
into itself or into the cæcum, or next to this the passage of the rectum
through the sphincter ani, to constitute eversion of the rectum. It
would appear to be possible at any part of the intestinal canal in the
horse, in which the bowels are more free to move than they are in
ruminants. Peuch records a case of invagination of the duodenum into the
stomach and Cadeac gives a woodcut of such a case, which one would
suppose the fixed position of the duodenum would render impossible. It
is conceivable that the jejunum could be invaginated into the duodenum,
and that this should have continued until it extended into the stomach,
but it is difficult to see how the duodenum itself could have passed
into the stomach without tearing itself loose from its connections with
the pancreas, liver and transverse colon.
Schrœder, Serres and Lafosse describe cases in which the small intestine
was everted into the cæcum and thence through the colon and rectum until
it protruded from the anus.
The invagination of the floating small intestine into itself is common
at any point, and extensive and even repeated. Marcout records a case in
which 24 feet were invaginated, and Rey a case of quadruple invagination
at the same point.
The invagination of the cæcum into the colon is frequent, the blind end
of the cæcum falling into the body of the same organ, and this
continuing to increase until it passes on into the colon, and even
carries a portion of the small intestine with it. This lesion is more
rare in solipeds because the cæcum has its blind end lowest and
gravitation opposes its invagination.
_Resulting Lesions._ In any case of invagination it must be noted that
it is not the intestine alone which slips into its fellow, but it
carries with it its attaching mesentery, which, dragging on one side of
the invaginated gut, shortens and puckers that and turns its opening
against the wall of the enclosing gut so as to block it, while the
opposite or free side passes on and tends to form convolutions. If the
outer and enveloping intestine is too small to allow of this, the
detaining mesentery of the invaginated mass must be torn or stretched
unduly and its circulation and innervation correspondingly impaired.
When the invagination occurs of one portion of the small intestine into
another of nearly equal size, the resulting mass is firm like a stuffed
sausage, and this enlargement and consolidation ends abruptly at the
point of visible entrance of the smaller contracted portion, into the
larger dilated one.
If recent, the invaginated mass is still easily disengaged from the
enveloping portion, though considerably congested and dark in color in
proportion to the duration of the lesion. When it has been longer
confined the incarcerated portion is the seat of extreme congestion, and
extravasation, and has a dark red or black color. The exudation into its
substance, which is especially abundant in the mucosa and submucosa,
produces a thickening which may virtually close the lumen, and on the
opposing peritoneal surfaces leads to adhesions which prevent the
extraction of the imprisoned mass. The interruption of the circulation
and the compression of the invaginated mass, leads soon to necrosis and
thus a specially offensive odor is produced, and if the animal survives
the whole may be sloughed off and passed with the fæces, the ends of the
intussuscepted portion and of that receiving it meanwhile uniting and
becoming continuous with each other.
_Symptoms._ These are the violent colic of obstruction of the bowels,
soon complicated by those of enteritis and finally of septic infection.
The animal looks at his flank, paws, kicks with his hind feet, lies
down, rolls, sits on his haunches, waves the head from side to side, and
sometimes eructates or even vomits. Straining may be violent, with the
passage of a few mucus-covered balls only, and rumbling may continue for
a time if the small intestines only are involved.
The partial subsidence of the acute pains, the presence of tremors,
dullness and stupor, the coldness of the ears and limbs, the small, weak
or imperceptible pulsations, the cold sweats, dilated pupils, and loss
of intelligence in the expression of the eye and countenance may
indicate gangrene, and bespeak an early death which may take place in
seven hours.
The subsidence of the acute symptoms with improvement in the general
appearance and partial recovery of appetite may indicate a spontaneous
reduction of the invagination, an issue which may happily arrive in any
case in the early stages, but especially in those implicating the cæcum
and colon.
An absolutely certain _diagnosis_ is rarely possible, unless the lesion
is a protrusion of the rectum, or unless as the disease advances the
invaginated part is sloughed off and passed per anum.
_Treatment._ The failure to make a certain diagnosis usually stands in
the way of intelligent treatment. Oleaginous laxatives and mucilaginous
gruels are advised to keep the contents liquid, and favor their passage
through the narrowed lumen of the invaginated bowel. In cases
implicating the floating colon and rectum abundant watery or
mucilaginous injections may assist in restoring a bowel which has not
been too long displaced. In case of eversion of the rectum, the hand
should be inserted into the protruding gut and carried on till it passes
through the sphincter ani. Then, by pushing it onward, the arm carries
in a portion of the invaginated gut and usually of the outer portion
next to the anus as well, and this should be assisted by the other free
hand, and even if necessary by those of an assistant, and whatever is
passed through the sphincter should be carefully retained, while the arm
is withdrawn for a second movement of the same kind, and this should be
repeated until the whole protruding mass has been replaced.
Invaginations situated more anteriorly and which can be correctly
diagnosed by rectal exploration or otherwise, will sometimes warrant
laparotomy, especially those of the cæcum into the colon, where adhesion
of the peritoneal surfaces is less common or longer delayed. The patient
should be given chloroform or ether, the abdominal walls should be
washed and treated with antiseptics, and the incision made back of the
sternum and to one side of the median line, and large enough to admit
the exploring hand. It has also been suggested to introduce the hand
through the inguinal ring, or behind the posterior border of the
internal oblique muscle.