Companion Animal
Soft Tissue Surgery
Surgery of the small intestine
Dr Stephen J Baines
MA VetMB PhD CertVR
CertSAS DipECVS
DipClinOnc MRCVS
Willows Referral Service
Highlands Road
Shirley
Solihull
West Midlands
B94 5QR
United Kingdom
stephen.baines@willows.
uk.net
1. Anatomy
The intestinal tract is approximately five times the length of the trunk in the dog
and cat. The small intestine is about four times the length of the large intestine and
measures between 1 and 1.5m in the cat and between 2 and 5m in the dog. Various
anatomical features allow identification of the different parts of the intestinal tract
at surgery which helps to avoid unnecessary manipulation and allows a rapid but
thorough exploration of the abdomen. The small intestine is narrower than the large
intestine, although transient physiological changes in diameter may not permit this
difference to be readily apparent. The duodenum is recognised by its position along
the right abdominal wall and by its relation to the stomach and pancreas. The jejunum
is smaller in diameter and is recognised by its length and relative emptiness. The
ileum may be identified by its thicker wall, by its additional peritoneal membrane, the
ileocaecal fold, which attaches to its antimesenteric border and by the extra blood
vessels (the ileal branches of the ileocaecal artery) within this fold. The jejunum and
ileum comprise 91% of the small intestine.
The intestinal tract is attached to the mesentery which permits ample mobility while
restricting excessive movement and supports, tethers and conveys nutrients to the
intestines. In addition, it is the mesentery which determines the topography of the
intestinal tract in situ. In its embryological development, the intestinal tract elongates
and twists more than 270o about the cranial mesenteric artery to form two interlocking
hooks or question marks, each with ascending, transverse and descending portions.
The coeliac artery divides into the splenic, left gastric and hepatic arteries. The latter
gives rise to the cranial pancreaticoduodenal artery which anastomoses with the
caudal pancreaticoduodenal branch of the cranial mesenteric artery. The majority
of the intestinal tract is supplied by the cranial mesenteric artery. It arises as a direct
branch of the aorta beneath the first lumbar vertebra, close to the coeliac artery, and
lies within the root of the mesentery in association with the mesenteric lymph nodes.
It rapidly divides into approximately a dozen major branches, some of which are
named according to the portion of the intestine they supply. They course in the great
mesentery, looping and anastomosing with their neighbours. Short vasa recti leave the
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arcades and extend directly to the intestinal wall, where they bifurcate on entry to pass
on either side of the intestine.
Lymphatic drainage of the duodenum is via the hepatic lymph nodes, which
lie either side of the portal vein, 1 to 2 cm from the hepatic hilus, and via the
pancreaticoduodenal lymph nodes, which consist of a small, constant node between
the pylorus and the right limb of the pancreas (duodenal node) and a smaller,
inconstant node in the ventral wall of the omental bursa a few centimetres from the
pylorus (omental node). Lymphatic drainage of the jejunum and ileum is via the cranial
mesenteric lymph nodes, which lie between the leaves of the long jejunal mesentery
along the cranial mesenteric artery and vein. The ileum is also drained by the right colic
lymph node which lies dorsomedial to the right colon at the ileocolic junction.
2. General considerations for small intestinal surgery
2.1. Pre-operative Concerns
Obstruction at the level of the pylorus or proximal duodenum results in the loss of
gastric fluid which is rich in sodium, potassium, chloride and hydrogen ions. Thus
metabolic alkalosis with hypochloraemia, hyponatraemia and hypokalaemia may result.
Most intestinal obstructions are distal to the bile and pancreatic ducts, resulting in
the loss of alkaline duodenal, biliary and pancreatic secretions resulting in metabolic
acidosis. Dehydration, due to fluid loss and inadequate intake, causes poor tissue
perfusion and the resulting lactic acidosis worsens the metabolic acidosis.
Bowel wall viability may be compromised by prolonged distension, pressure
necrosis from lodged foreign bodies, traumatic damage to the blood supply and
strangulating obstructions. This results in increased permeability to endotoxins and
bacteria. Inadequate tissue perfusion from hypovolaemia may therefore develop into
endotoxaemic shock.
Those patients which are likely to have poor visceral healing should be identified preoperatively. This may prompt postponement of an elective procedure until the patient’s
condition has improved, or may allow appropriate intra-operative measures to be
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taken to minimise the risk, such as choice of suture material, omentalisation and serosal
patching.
Ideally animals should be fasted for 12 to 18 hours prior to surgery, but in paediatric
patients and very small individuals (e.g. less than 3 kg) this should be reduced to 4-8
hours. Fluid, electrolyte and acid-base imbalances should be corrected before surgery if
possible. If not, then an attempt to replace at least 50-75% of the volume deficit should
be made.
The presence of visceral distension may compress the caudal vena cava, resulting
in circulatory compromise, and may displace the diaphragm cranially, resulting in
ventilatory compromise. Patients with a history of vomiting may be at risk of vomiting
and aspiration on induction of anaesthesia.
2.2. Intra-operative Concerns
The surgeon should aim to minimise contamination, maintain tissue viability,
handle tissue atraumatically and promote early union of divided tissue by the use of
appropriate suturing techniques.
The use of a suitable retractor, e.g. Gosset or Balfour, will improve access to and visibility
of the intestinal tract. The edges of the wound should be protected by saline-soaked
swabs or laparotomy pads. Intestinal tissues are fragile and should be handled gently.
The use of atraumatic thumb forceps e.g. DeBakey pattern will produce less tissue
trauma.
Intestinal contents are excluded from the surgical site by milking the luminal contents
orally and aborally and then occluding the lumen of the bowel with an assistant’s
fingers or bowel clamps. Occluding the lumen with fingers is the least traumatic
method. Both crushing and non-crushing clamps may be used. The crushing clamps are
used to clamp the end of the resected segment, and the atraumatic forceps are used
to occlude the lumen of the segments to be anastomosed. Crushing forceps can be of
any type which conveniently fits across the intestine (e.g. Carmalt, Allen). Doyen forceps
are the traditional atraumatic forceps; paediatric forceps may be of more use in small
animal patients. If an assistant is available, then occluding the lumen with the fingers is
the least traumatic method.
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Every effort should be made to minimise bacterial contamination of the peritoneal
cavity during surgery. The affected segment of intestine is exteriorised and packed off
from the rest of the abdominal contents with saline-soaked sponges. Intestinal contents
are milked out of the segment to be operated on before the application of forceps
and suction is used to reduce any spillage of intestinal contents. The use of impervious
drapes helps prevent bacterial strike-through, which is more likely when peritoneal
fluid is present or when saline irrigation is carried out. Instruments and equipment used
during the enterotomy or enterectomy are discarded after that procedure is completed,
gloves and, if necessary, gowns, are changed and the peritoneal cavity is thoroughly
lavaged with warm sterile saline. Closure of the mesenteric defect and abdominal wall is
then performed with clean instruments.
2.2.1. Assessment of intestinal viability
Vascular compromise of the intestines may occur with venous occlusion
(intussusception, torsion, foreign body, strangulated hernia), arterial occlusion (cranial
mesenteric artery thrombosis) and arteriovenous injury (mesenteric vessel avulsion).
These conditions may cause ischaemic necrosis of the intestinal wall. Assessment
of the viability of a segment of intestine may be difficult and should be performed
after removal of fluid and gas from dilated loops of intestine. Decompression may
be performed with a 19-21 gauge needle, a 60 ml syringe and a three-way tap. The
involved portion of intestine may be wrapped in a warm, saline-soaked swab for 5
minutes and then re-inspected.
The standard clinical criteria are colour, arterial pulsations, peristalsis, wall texture and
sheen, and bleeding on incision. Of these, peristalsis is the most reliable criterion of
viability. However, these criteria are subjective and not consistently reliable.
Clinical judgement is more accurate in strictly venous occlusions, in which the colour
is blue/black and the intestine is flaccid, than in cases of arterial injury where the
colour may be nearly normal and small vessel thrombosis may be invisible. In addition,
a normal appearance does not guarantee that the intestine will heal normally after
surgery. In there is any doubt, more intestine should be resected.
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A number of techniques have been proposed to increase the accuracy of prediction
of intestinal viability. The use of electromyography, radioactive microspheres and
microtemperature probes has been suggested, but these are expensive, technically
cumbersome and not generally suited for clinical use. Doppler ultrasonic flow probes
to detect pulsatile mural blood flow and pulse to assess arterial perfusion of ischaemic
intestine have been used with some success.
The assessment of vascularity following intravenous injection of fluorescein dye has
been reported to be the most sensitive method. Fluorescein is injected into a peripheral
vein and the pattern of fluorescence is observed with a Woods lamp in a darkened
theatre. Viable intestine has fluorescing areas of a smooth, uniform green/gold colour
with no areas of non-fluorescence greater than 3 mm. This is really a test of vascularity
rather than viability, and does not give any indication of the integrity of the mucosal
barrier. In addition, this technique is rarely available promptly when it might be needed.
In most settings, the most accurate assessment of bowel viability is provided by the eye
of an experienced surgeon.
2.2.2. Choice of suture material and needle
A wide range of suture materials has been successfully used for intestinal anastomosis
and the selection of suture material frequently depends on the surgeon’s preference.
Absorbable suture materials are often recommended on the grounds that the intestinal
tract heals rapidly and suture tensile strength is only required for a short period of
time. Multifilament absorbable suture materials e.g. polyglactin 910 (Vicryl; Ethicon)
and polyglycolic acid (Dexon; Davis & Geck), have good knot security and handling
characteristics compared with monofilament materials. However, they have greater
tissue drag, an increased likelihood of cutting through the intestine and may harbour
bacteria in the interstices of the material.
In most cases, the use of a synthetic absorbable monofilament material is the
better choice. Polyglecaprone (Monocryl; Ethicon) combines the advantages of low
tissue drag, ease of handling, and appropriate duration of suture. In compromised
patients, the use of slowly absorbable material e.g. polydioxanone (PDS; Ethicon)
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or polyglyconate (Maxon; Davis & Geck) or non-absorbable suture material e.g.
polypropylene (Prolene; Ethicon) or nylon (Ethilon; Ethicon) is recommended. Nonabsorbable suture material will be extruded into the lumen with time and should not
pose a long term problem as foreign bodies.
Chromic catgut is not recommended because it loses tensile strength rapidly in the
presence of collagenase and is quickly phagocytosed in an infected environment. In
addition, the inflammatory response it invokes may lead to fibrosis and luminal stenosis.
Braided non-absorbable suture material should be avoided since it may harbour
bacteria in the interstices and may provoke a granulomatous reaction.
Atraumatic taper-point needles have been advocated for intestinal surgery because
they create a round hole during passage through the tissues, making suture ‘cut
through’ less likely. However, these needles are more difficult to pass through delicate
visceral tissues, and their use may be associated with more tissue trauma than the
use of reversed-cutting needles, particularly from excessive use of thumb forceps to
stabilise the tissues during suture passage. Cutting-tipped atraumatic needles are a
compromise.
Suture size may range from 3 metric (2/0) to 1.5 metric (4/0) depending on the size of
the patient and the anastomotic site. Sutures are generally placed 2 to 3 mm from the
cut edge and 2 to 4 mm apart.
In the healthy patient, the suture material selected may be less important than the
technique of suture application.
2.3. Post-operative care
The animal should be monitored closely for vomiting during recovery. Adequate
analgesia should be provided, for instance with a multimodal approach using
opiates, non-steroidal anti-inflammatory drugs and local anaesthesia. Prophylactic
antibiotics given in the case of clean-contaminated or contaminated surgeries may be
discontinued within 24 hours, provided that adequate intra-operative management
of the wound (debridement and lavage) is provided. In the case of dirty surgeries,
antibiotic use is therapeutic and should continue for 2 to 3 days beyond the resolution
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of clinical signs. In this case, the suitability of the empiric pre-operative choice of
antibiotic should be confirmed by culture of infected tissue.
Fluid therapy should take account of replacing any deficit not corrected before surgery
and any deficit incurred during surgery, replacing any continuing losses (e.g. from
vomiting or diarrhoea) and providing maintenance fluids until the animal is able to
maintain its own hydration. Electrolyte and acid-base balance should be monitored and
corrected, at least on a daily basis, until the animal is eating and drinking normally.
Feeding should begin as soon as the patient is able to tolerate it. Feeding stimulates
motility and blood flow in the intestinal tract, reduces the likelihood of ileus and
adhesions and is a valuable source of fluid and electrolytes. Delaying feeding in an
attempt to minimise leakage at the site of enterotomy or enterectomy is not rational,
since ingesta and secretions from the proximal intestinal tract will be present at the
intestinal wound as soon as the clamps are removed. Similarly, delaying feeding in
an attempt to reduce tension on the intestinal suture line is inappropriate since the
migrating motor complexes are greater in magnitude in the fasted state compared with
the fed state. In addition, any delay in the post-operative nutrition of the patient may
increase the duration of the lag phase of healing.
Various abnormalities may exist post-operatively, which will influence the choice
of diet. Some degree of ileus may be present, as a result of the disease process or
surgical manipulation of the intestine; there may be a change in the numbers, nature
and distribution of the intestinal bacterial flora because of the disease and the use of
antibiotics; and there may be damage to the intestinal villi and tight junctions between
enterocytes. The requirements should be tailored to the patient. Those animals with a
focal lesion (e.g. adenocarcinoma) removed by resection and anastomosis will return to
normal feeding more rapidly than patients with a more extensive disease process (e.g.
multiple perforations from a linear foreign body).
For these reasons, a highly-digestible diet, which is low in fat and low in fibre, has much
to recommend it. This may be achieved using a commercial diet, such as Hills i/d, or
a home made diet consisting of boiled rice, potatoes or pasta combined with boiled
skinless chicken, low-fat cottage cheese or yoghurt. Three or four small meals should be
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fed daily. The normal diet may then be re-introduced gradually, beginning 48-72 hours
post-operatively, at which time a reasonable appetite should be present. Debilitated
patients may require enteral tube feeding.
After intestinal surgery, animals must be closely monitored for signs of peritonitis.
Depression, abdominal pain greater than that expected after surgery, splinting of
the abdominal wall, lack of intestinal sounds, vomiting and pyrexia may be present
with peritonitis. If peritonitis is suspected, blood should be submitted for routine
haematological and biochemical screens, and abdominal paracentesis or diagnostic
peritoneal lavage should be performed.
2.6. Principles of small intestine anastomosis
2.6.1. Orientation of the resected ends
The surgical literature is replete with studies evaluating and comparing various
methods of intestinal anastomosis. Anastomosis can be performed using an end-toend, an end-to-side or a side-to-side technique. The latter two are technically more
demanding, more time-consuming, involve two or three more suture lines and do not
reconstruct the intestinal tract in a physiological fashion. Thus the use of an end-to-end
anastomosis is recommended throughout the intestinal tract.
2.6.2. Types of end-to-end anastomosis
The main types of anastomotic reconstruction are the approximating, inverting,
everting and invaginating patterns.
2.6.2.1. Approximating techniques
This technique was developed to improve intestinal healing by accurate realignment of
the cut layers of the intestinal wall and to minimise the possibility of luminal reduction.
It is easier to place than the inverting techniques and its bursting strength is the same
or greater after 24 hours. This pattern is associated with quicker regeneration of mucosa
over the incision, less fibrous connective tissue deposition and less inflammation than
the inverting or everting techniques and reduced incidence of adhesion formation. This
technique is recommended for use throughout the small intestine.
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2.6.2.2. Inverting techniques
The inverting pattern is the classic technique for human intestinal anastomosis. A single
layer closure using a Connell, Cushing or Halsted pattern has been described, as well
as a double layer closure using a Connell or Cushing pattern first and then a Halsted or
Lembert pattern. Inversion of the intestinal wall causes compression of blood vessels
and reduction of blood flow to the inverted portion. The inverted portion shows
necrosis and oedema 3 days after surgery and has usually sloughed at 5 days after
surgery. At 7 days, vessels have crossed the incision and at 14 days a scar bridges the
suture line, but the layers have not reformed.
This technique has a greater bursting strength than the approximating technique
immediately post-operatively, but this advantage is lost after 24 hours. A two layer
inverting closure has the greatest tensile strength; a single layer inverting technique is
similar to the approximating pattern in this respect. The continuous inverting Cushing
pattern has been recommended by some surgeons for intestinal wound closure in
compromised patients, because of its superior bursting strength. Inverting anastomoses
are less likely to leak, but the internal cuff of tissue may cause luminal stenosis and
healing time is slower than for approximating techniques. Despite its apparent
advantages with respect to tensile and anastomotic strength, the reduction in luminal
diameter seen with this technique is sufficient reason to choose an approximating
technique.
2.6.2.3. Everting techniques
This was developed in an effort to minimise the reduction in luminal diameter which
accompanies inverting techniques. A horizontal mattress pattern has been described
to evert all layers of the wall. The natural tendency of the intestines to evert makes
placement of this pattern relatively simple.
The everted mucosa undergoes necrosis. Inflammation is prolonged and mucosal
healing and resumption of normal vascular flow is delayed compared with an inverting
pattern. The everted mucosa also causes more inflammation at the serosal surface,
peritoneal inflammation is enhanced and adhesions are more likely with this technique.
Ultimately, this inflammation leads to stenosis and narrowing of the intestine. This
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technique has the weakest bursting strength in the immediate post-operative period
and leakage is more likely with this suture pattern. Data about its tensile strength is
conflicting.
2.6.2.4. Invaginating techniques
This complex technique involves pulling the distal segment of bowel into the proximal
segment with mattress sutures and allowing the invaginated portion of the distal
segment to slough. A further modification involves removing the mucosa from
the one segment and the muscularis from the other segment and telescoping the
segments with pre-placed sutures. This technique is technically difficult and cannot be
recommended.
2.6.3. Stapled anastomoses
Stapled anastomoses show a greater blood flow, a much higher bursting strength and a
negligible lag period. Stapled anastomoses show good anatomical layer alignment, but
more inflammation than suture techniques.
2.6.4. Suture patterns for approximating end-to-end anastomoses
Approximating anastomoses can be achieved with a simple continuous pattern or
with one of three interrupted patterns; simple interrupted, Gambee or Poth and Gold
crushing suture. Practically, only the simple interrupted and simple continuous patterns
are recommended.
The simple interrupted suture passes through all layers on either side of the wound
and is tied to hold the layers in apposition. The Gambee pattern is a simple interrupted
suture that penetrates the lumen and then returns through a small segment of mucosa
and submucosa on the same side, before crossing the anastomotic site at the level
of the submucosa. A modified Gambee suture engages the submucosa but does not
penetrate the mucosa. Exclusion of the mucosa at the anastomotic site helps to prevent
mucosal eversion, but this suture is difficult to place given the small diameter of the
intestine in cats and dogs.
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The Poth and Gold pattern is a simple interrupted suture that is tied with sufficient
tension to cut through the mucosa from beneath and the serosa and muscularis from
above and holds the submucosa in apposition. This technique produces more tissue
necrosis and vessel disruption at the anastomotic site during the first week compared
to the non-crushing appositional technique and is more likely to result in mucosal
eversion or tissue overlap between sutures. Bursting pressure of both techniques are
similar. The continuous approximating pattern causes less mucosal eversion and fewer
post-operative peritoneal adhesions than the interrupted patterns. It also results in
more precise submucosal apposition between sutures, provides better haemostasis and
results in rapid mucosal healing.
Experimental evaluation of healing, strength of anastomosis, compromise of luminal
diameter and adhesion formation indicate an advantage of approximating techniques
over inverting or everting techniques. Simple interrupted or simple continuous
sutures are preferred over a crushing pattern. Regardless of the suture pattern used,
incorporation of the tough, collagen-rich submucosa and prevention of mucosal
eversion are vital for a successful anastomosis.
2. Surgical techniques for small intestinal surgery
2.1. Intestinal biopsy
An elliptical, longitudinal, full-thickness biopsy specimen is removed from the
antimesenteric border of the intestine using a scalpel and fine scissors and atraumatic
forceps. Alternatively, a Keyes biopsy punch may be used. It should be ensured that all
layers of the intestine are present in the biopsy specimen, and the specimen laid flat,
serosal side down, on a piece of paper or card (e.g. the card insert in a packet of suture
material) to prevent it rolling up prior to being placed in fixative. The defect is closed
with simple interrupted sutures. This may be performed in a longitudinal manner, or
may be closed transversely to reduce the likelihood of luminal obstruction.
2.2. Enterotomy
Indications for enterotomy include the removal of foreign bodies and inspection of the
mucosa for evidence of ulceration, stricture or neoplasia. Management of the latter
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conditions is chiefly by intestinal resection and anastomosis. The enterotomy site is
chosen distal to the lesion to avoid incising into the devitalised bowel at the lesion or
the dilated bowel proximal to it. Intestinal contents are expressed from the enterotomy
site and the bowel is occluded by an assistant’s fingers or with atraumatic clamps. A fullthickness incision is made in the antimesenteric border with a scalpel and enlarged as
necessary with scissors. The foreign body is removed through the incision, which should
be large enough to avoid tearing the wound margins. The bowel lumen is examined for
the presence of ulceration, perforation or stricture. Suction is used to remove residual
intestinal contents and any everted mucosa is trimmed with scissors before closure.
The defect is closed with a simple interrupted or simple continuous suture pattern.
Transverse closure of the wound may be performed if the enterotomy was performed
in bowel of small diameter. The enterotomy site is lavaged with warm sterile saline,
covered with omentum and replaced into the abdominal cavity.
2.3. Intestinal resection and anastomosis
Intestinal resection and anastomosis is indicated for the removal of devitalised or
perforated bowel, for resection of mural lesions including strictures and tumours and
in the management of extramural lesions such as adhesions and abdominal abscesses
which obstruct adjacent intestine.
The affected portion of the intestine is exteriorised and the segment of intestine to be
removed is selected after the vascularity and viability of the intestine has been assessed.
Crushing clamps are placed across the intestine adjacent to the diseased segment. The
clamps are placed perpendicular to the axis of the intestine or angled up to 30o toward
the normal segment to ensure adequate blood supply to the antimesenteric border. The
intestinal contents are then milked away from the site of resection and non-crushing
intestinal forceps are then placed approximately 4-6 cm from the crushing clamps.
The jejunal branches of the cranial mesenteric artery that supply the segment of
intestine are clamped and ligated or doubly ligated and then transected. If peritonitis
is present, these vessels may be difficult to identify and transillumination of the
mesentery may improve visualisation. The terminal arcade adjacent to the intestinal
wall is doubly ligated at either site of transection. The vasa recti that leave the terminal
arcade are not ligated. The terminal arcade may be difficult to visualise in obese animals;
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passing the needle directly adjacent to the mesenteric border will allow ligation of
these vessels without penetrating them. The mesentery is then incised between the
doubly ligated vessels and the intestine is sharply transected with a scalpel at the level
of the crushing clamps, passing between the two ligatures in the terminal arcade. The
diseased segment of intestine is then removed.
Intestinal contents adherent to the exposed intestinal mucosa are gently removed with
moist gauze swabs. Arterial bleeding from the cut ends is controlled with ligation or
diathermy and venous bleeding is controlled by pressure with a gauze swab. Arterial
bleeding should not be present if all vessels have been identified and ligated. The
everted mucosa is trimmed with scissors to create a level surface for suturing the
intestinal wall. This may need to be repeated as the anastomosis continues.
If a simple interrupted pattern is selected, initially one suture is placed at the mesenteric
border and one at the antimesenteric border. The suture at the mesenteric border is
placed first because the presence of fat makes suture placement most difficult and this
is the most common site for leakage. These are used as stay sutures to aid manipulation
and alignment of the anastomotic site as further interrupted sutures are placed.
If a simple continuous pattern is selected, this is started at the mesenteric border,
and continued to the antimesenteric border to end at the mesenteric border. This
suture may be interrupted once or twice over the circumference of the anastomosis.
Alternatively two further simple interrupted sutures may be placed in addition to those
at the mesenteric and anti-mesenteric borders. A simple continuous suture pattern is
placed between each of these quadrant sutures.
The defect in the mesentery is then sutured, avoiding the jejunal vessels. A simple
interrupted or continuous pattern may be used with suture bites perpendicular to the
free edge of the mesenteric defect. Alternatively, the mesentery may be elevated on
each side of the defect in the jaws of a haemostat and an encircling ligature placed
around this cuff of tissue. This suture has greater holding power, but may cause
ischaemia to a greater portion of tissue.
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2.4. Management of luminal disparity
Following enterectomy, the diameters of the segments to be anastomosed may be
different, and a number of different techniques are available to manage this.
With minor luminal disparity, the spacing between sutures is made greater in the
segment with the larger diameter, and an end-to-end anastomosis without gaps
or puckering is obtained. With moderate luminal disparity, the smaller segment of
intestine is transected at an angle of 45-600 rather than perpendicular to its long axis,
thus effectively enlarging the intestinal diameter. With marked luminal disparity, the
end of the segment with the smaller diameter is spatulated with a 1 – 2 cm longitudinal
incision in the antimesenteric border, after which two triangular flaps may be trimmed
off. Stay sutures are placed at the mesenteric and antimesenteric borders and the
anastomosis is completed. Partial closure of the antimesenteric border of the larger
segment has been suggested as a technique to manage luminal disparity, but, given
that preservation of luminal diameter is of prime importance in intestinal surgery, this
technique is less satisfactory. In addition, the junction between the partly-closed larger
segment and the antimesenteric border of the smaller segment is a potential site of
leakage or dehiscence. Gross luminal disparity may necessitate an end-to-side or sideto-side anastomosis.
2.5. Enteroplication
This is the fixation of the small intestine to itself to form a series of gentle loops. It
is indicated in the prevention of recurrence of intussusception, and as a technique
to reduce the complications associated with adhesion formation in this part of the
intestinal tract. Intussusception has a recurrence rate of up to 25% if this technique is
not performed. In conditions in which adhesion formation is likely, such as extensive
serosal damage from trauma or other disease process, or following resection of
pathologic adhesions, enteroplication promotes the formation of more orderly
intestino-intestinal adhesions rather than random adhesions.
The small intestine is exteriorised and laid into a series of gentle loops in a zig-zag
pattern. The loops are secured in this position by placing simple interrupted sutures
between adjacent parts of intestine, approximately 6 to 10 cm apart and midway
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between the mesenteric and anti-mesenteric border. The sutures should engage the
submucosa. Plication of the small intestine from the duodenocolic ligament to the
ileocaecocolic ligament is generally recommended.
2.6. Omentalisation and serosal patching
The omentum has a role in plugging hernial defects, sealing off focal areas of infection
or perforation and bringing a new vascular supply and leucocytes to a compromised
area. All anastomoses leak to some extent; a successful anastomosis depends on the
natural resistance provided by peritoneal and omental function.
The surgical site is inspected to ensure adequate apposition and the absence of leaks.
The site is lavaged gently with warm sterile saline to remove any blood clots and
covered with omentum. The omentum may be simply wrapped around the surgical site,
or tacked with a small number of interrupted sutures.
Serosal patching serves to provide support, a fibrin seal, resistance to leakage and
blood supply to the affected area. Patches are indicated when partial rather than
segmental resection of a portion of intestine is performed (e.g. preservation of the
proximal duodenum at the opening of the bile duct and pancreatic duct). Patches that
span visceral defects are covered with mucosal epithelium within 8 weeks. A loop of
jejunum adjacent to the area in question is generally used, although any part of the
intestinal tract or urinary bladder may be used. The serosal surface of the adjacent
piece of bowel is approximated to the defect or focal devitalised area. The two pieces of
intestine are then sutured together, with sutures penetrating the submucosa, in healthy
tissue beyond the devitalised tissue in the segment to be patched. Two pieces of bowel
may be used to provide a larger patch; in this case these loops are sutured together
before patching.
2.7. Enterostomy tube placement
Enteral feeding via this route is indicated when gastric atony, gastroduodenal
obstruction, neoplasia, regurgitation or vomiting prevents feeding by a more proximal
site. Patients requiring extensive surgical procedures of the stomach, duodenum,
pancreas or hepatobiliary system can also be provided with immediate post-operative
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support. Contraindications include adynamic ileus of the small intestine, persistent
diarrhoea and intestinal obstruction distal to the feeding tube. Tube placement is
a relatively simple technique. However, the nutritional management of the patient
following tube placement is more demanding, and this technique should not be
performed without some knowledge of the care required.
The tube may be placed in the descending duodenum or proximal jejunum. The
enterostomy site is selected in a loop of intestine that can be approximated against the
abdominal wall without tension. A purse-string suture is placed on the antimesenteric
border of the selected portion of intestine.
If a tube of uniform diameter with a detachable syringe adapter is used, then a throughthe-needle technique may be adopted. A 12 or 14 gauge catheter is passed, bevel up,
through the centre of the purse-string and directed sub-serosally 1-2 cm in an aboral
direction before entering the bowel lumen. The feeding tube is then passed through
the needle and advanced 20-30 cm. The needle is withdrawn and the purse-string
suture tightened around the feeding tube. The needle is then passed obliquely from the
skin surface through the abdominal wall into the peritoneal cavity, and the proximal
end of the feeding tube passed retrograde through the needle.
If an enterostomy tube with an integral syringe adapter is used, then a stab incision
is made in the skin, and the tube placed antegrade through the abdominal wall in a
tunnel made by haemostats. A stab incision is then made in the centre of the pursestring suture in the intestine and advanced aborally along the lumen of the intestine for
20-30 cm. Alternatively, a retrograde through-the needle technique may be used, where
a 12 or 14 gauge catheter is introduced into the intestine aboral to the site of tube
entry, passed along the intestinal lumen in an oral direction, and then exited from the
intestine obliquely. The feeding tube is then introduced into the catheter tip and the
catheter and tube brought into the intestinal lumen. The catheter is then removed from
the intestine and the hole is sutured closed.
The purse-string suture is then tightened and tied. The loop of bowel is secured against
the abdominal wall with several interrupted sutures. A piece of omentum should be
incorporated around this enteropexy. The tube is fixed to the skin surface with a tape
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butterfly or a Chinese finger-trap friction suture. The tube should remain in situ for at
least 5 to 7 days to allow adhesion formation. The tube is removed easily after removing
the external skin sutures.
Enterostomy tube feeding may begin after recovery from anaesthesia provided that
peristaltic movements were noted at the time of tube placement. Because of the lack
of a physiologic reservoir and the high osmolality of some commercial liquid diets, an
animal with an enterostomy tube should be fed by continuous gravity or pump infusion
or by hourly slow bolus administration. Feeding should be started slowly (0.5-1 ml/kg/
hour) and increased over 2 to 4 days until the daily requirement is reached. Osmotic
diarrhoea is a relatively common complication.
4. Diseases of the small intestine
4.1. Small intestinal obstruction
Obstruction is the most common indication for intestinal surgery. Strangulating
obstructions involve compromise of the enteric blood supply, whereas simple
obstructions do not. The obstruction may be described as complete or partial, the latter
being more difficult to diagnose.
The nature and site of obstruction influence the clinical signs. Proximal small intestinal
obstruction stimulates vomiting with loss of acidic gastric secretions and alkaline
secretions from the gall-bladder, pancreas and duodenum. Dehydration, electrolyte
imbalance and a normal pH or primary metabolic acidosis will result. Metabolic acidosis
is due to the relatively greater loss of alkaline intestinal fluids and may also result from
dehydration and inadequate tissue perfusion. Obstruction of the distal jejunum or
ileum may not stimulate vomiting, but result in distension of the intestinal lumen with
fluid and gas.
Strangulating obstruction may result from incarceration of the intestine in a hernia
or twisting of the mesentery. The mesenteric circulation is interrupted and tissue
necrosis follows. Tissue necrosis may also result from prolonged distension and pressure
necrosis from lodged foreign bodies. Definitive diagnosis of the cause may require an
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exploratory laparotomy and the surgeon should be prepared to perform any of the
techniques listed above.
4.2. Linear foreign body
Typically, part of the linear foreign body lodges orally within the intestinal tract, either
at the base of the tongue or at the pylorus, with the remainder progressing some
distance aborally along the intestinal tract. Peristaltic waves attempting to advance the
object cause the intestine to be gathered around it in accordion-like pleats. Continued
peristalsis causes the foreign body to become taut and saw through the mesenteric
border of the intestine.
Conservative therapy, consisting of cutting the foreign body at its sublingual location
and allowing its passage through the intestine is not associated with a uniformly good
outcome, and cannot be recommended. Surgical exploration of the abdomen should
follow cutting of the linear foreign body at the base of the tongue. A gastrotomy
may be required if the material is anchored at the pylorus. An enterotomy is made
midway along the site of obstruction and as much of the foreign body removed by
gentle traction. The ends are then cut. Additional enterotomies are spaced out along
the intestine to ensure removal of all the foreign body, while minimising the risk of
lacerating the intestine. Areas of non-viable bowel, or where perforation has occurred,
should be resected. In the chronic case, perforation followed by fibrosis may have
occurred sometime previously, and the bowel retains its pleated conformation after
removal of the foreign body. In this case, resection and anastomosis may be necessary.
A single enterotomy catheter technique has been described to remove linear foreign
bodies. An incision is made into the stomach or intestine where the linear foreign body
is fixed. The end of the object is sutured to a soft catheter or red rubber feeding tube
and the catheter introduced into the intestine. The enterotomy site is closed and the
catheter and attached foreign body milked aborally along the intestinal tract and out
through the anus.
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4.3. Intussusception
Intussusceptions, caused by the invagination of a portion of intestine (the
intussusceptum) into an adjacent segment (the intussuscipiens), occur primarily at the
ileocolic valve and in the jejunum. Most intussusceptions are considered idiopathic, but
predisposing factors include parasitism, enteritis, a linear foreign body, an intestinal
mass (polyp, granuloma, neoplasm or congenital enterocyst) and prior abdominal
surgery. Severe cases may result in prolapse of the intussusceptum per rectum (rectal
intussusception) and need to be differentiated from rectal prolapse. In the former
situation, a probe or thermometer can be passed between the prolapsed portion of
intestine and the anus, whereas in rectal prolapse it cannot.
A thorough search of the abdomen should be made, since intussusceptions at multiple
sites may be present. An attempt should be made to reduce the intussusception
manually. The intussusception is squeezed while gentle traction is applied to the
intussusceptum. This will only be possible if fibrous adhesions have not formed. If,
during reduction, the serosal surface, with or without a portion of the muscularis, splits,
but the bowel appears viable, then these small lacerations may be closed with simple
interrupted sutures. If the intussusception cannot be reduced, or if after reduction, the
segments of intestine are not viable, then resection and anastomosis is indicated. In all
cases, enteroplication should be performed to reduce the risk of recurrence.
4.4. Intestinal tumours
Tumours of the small intestine are uncommon in the dog and cat, and represent less
than 1% of all malignancies. Benign intestinal tumours are even less common. Extension
of adjacent primary tumours (e.g. pancreatic or biliary) to involve the duodenum is
occasionally encountered. In dogs, adenocarcinoma and lymphosarcoma are the most
common. Lymphosarcoma is the most common in the cat, followed by adenocarcinoma
and mast cell tumour.
The location and extent of the tumour determine the possibilities for surgical treatment.
Definitive diagnosis and clinical staging of small intestinal tumours requires evaluation
at laparotomy. The extent of resection required to excise the primary lesion can then
be determined. Regional lymph nodes, the liver, kidneys, mesentery and lungs are
Abstracts | European Veterinary Conference Voorjaarsdagen 2016
the common sites for metastasis and should be examined directly, radiographically or
ultrasonographically.
In most cases, wide local excision with margins extending several centimetres (4-8
cm) beyond the tumour can be performed by enterectomy. Rarely is the resection
compromised by lack of adjacent normal tissue. However, the resection of duodenal
lesions may be complicated by the need to preserve biliary and pancreatic ducts, and
may necessitate serosal patching techniques to preserve the proximal bowel. Adhesions
associated with tumour growth are common and may require a more extensive
resection. Perforation of the bowel in the region of the tumour may lead to localised, or
occasionally, generalised, peritonitis, and may require abdominal lavage and drainage
procedures.
In the presence of regional lymphadenopathy, an attempt is made to remove those
lymph nodes en bloc with the primary lesion. Enlarged lymph nodes not contained
within the tissue to be resected should be subject to incisional or excisional biopsy. It is
not possible to differentiate reactive nodes from those containing metastatic deposits
by gross inspection and all excised lymph nodes should be subject to histological
analysis.
In the case of diffuse infiltrative tumours, laparotomy and intestinal biopsy is indicated
to achieve a definitive diagnosis. Surgery is indicated in suspected cases of lymphoma
where obstruction or bowel perforation has occurred.
Adenocarcinoma may be annular or intraluminal. Metastasis to mesenteric lymph
nodes may occur, or may occasionally result in marked mesenteric and omental
sclerosis. Complete resection of well-differentiated adenocarcinomas in the absence
of metastatic disease has a favourable prognosis with local recurrence or secondary
extension of the disease unlikely. Local infiltration and metastasis indicate a poorer
prognosis. In one report of intestinal adenocarcinoma in the cat, the average survival
time of those animals alive 2 weeks after surgery was 15 months and 12 months for
those cats with confirmed mesenteric lymph node metastasis. However, 50% of the
cats died or were euthanised within 2 weeks of surgery. Complete excision of a benign
adenomatous polyp has an excellent prognosis.
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Most dogs with alimentary lymphoma present with diffuse involvement of the intestinal
tract and solitary lesions are rare. In the cat, solitary or diffuse lesions may be present,
with or without involvement of the mesenteric lymph nodes or liver. Chemotherapy
for diffuse lymphoma in the dog is unrewarding. However, surgical resection of
early (Stage I) intestinal lesions followed by chemotherapy has a more favourable
prognosis. Chemotherapy of diffuse intestinal lymphoma in the cat with vincristine,
cyclophosphamide, methotrexate and prednisolone (VCM) was associated with a
50% response rate and a median survival time of 9.6 months and with vincristine,
cyclophosphamide and prednisolone (COP) with an 86% response rate and a median
remission time of 4.5 months.
Visceral mast cell tumours are uncommon in the dog, but are seen with reasonable
frequency in cats. Feline mast cell tumours may be found anywhere throughout the
small intestine and may be solitary or multiple. They are associated with widespread
dissemination, involving the spleen, liver and regional lymph nodes, although
peripheral blood smears do not usually reveal mast cells. Prognosis is poor for small
intestinal mast cell tumours, although those restricted to the spleen may have a more
favourable prognosis. Leiomyosarcomas are locally invasive malignancies which are
slow to metastasize, although extension to regional lymph nodes is reported. Although
substantial data is lacking, in the absence of metastasis, leiomyosarcomas may have a
favourable prognosis, one report demonstrating a 60% one year survival. The prognosis
following complete resection of a leiomyoma is good to excellent. Carcinoids, tumours
of enterochromaffin cells in the intestinal mucosa, occur rarely in the dog and cat.
Although often slow-growing, they tend to infiltrate locally and metastasize and
insufficient data is available to predict the prognosis.
ischaemic damage to a large proportion of the small intestine followed by development
of endotoxaemia. The degree of rotation, severity of the ensuing distension of the
intestine and duration of the volvulus determine the degree of the ischaemic insult.
Mortality approaches 100%. In previous reports, those patients that survived had a
diagnosis made during laparotomy for a different problem, had rotation limited to 1800
and were operated on within a few hours of occurrence. Surgical management involves
decompression and derotation of the intestines and resection of devitalised bowel.
Massive intestinal resection may be required and may result in short bowel syndrome.
4.6. Intestinal trauma
Trauma to the small intestine is uncommon. Causes include bite wounds to the
abdomen, penetrating injuries of the abdominal wall, blunt trauma, e.g. following
a road traffic accident, and trauma after evisceration following dehiscence of an
abdominal incision. Penetrating wounds and contusions of the intestinal wall and
shearing or laceration of the mesenteric attachments, with subsequent damage to the
vascular supply and necrosis may result. Suspected intestinal injuries are best evaluated
by careful abdominal palpation, radiography and abdominal paracentesis. Given the
serious consequences of unrecognised and untreated intestinal leakage and the low
morbidity associated with exploratory laparotomy, direct examination of the peritoneal
cavity should be performed if there is any doubt about the integrity of the intestinal
tract. Small wounds may be debrided and closed primarily. Larger defects may require
serosal patching. More extensive injuries should be managed with resection and
anastomosis.
4.5. Mesenteric torsion
Mesenteric torsion is rare in dogs and results from a rotation of the intestine about its
mesenteric axis. The duodenum is usually not involved, because of its relatively fixed
position in the abdominal cavity. Vigorous activity, dietary indiscretion, trauma or
exocrine pancreatic insufficiency may predispose to volvulus. The root of the mesentery
twists and the cranial mesenteric artery and vein, or their branches, are obstructed. A
mechanical and strangulating obstruction results and there is rapid development of
Abstracts | European Veterinary Conference Voorjaarsdagen 2016
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