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Surgical Management of Abdominal Trauma
Howard B Seim III, DVM, DACVS
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General principles and techniques
Definitions
Celiotomy is a surgical incision into the abdominal cavity; the term laparotomy often is
used synonymously, although it technically refers to a flank incision. A sudden onset of
clinical signs referable to the abdominal cavity (e.g., abdominal distention, pain,
vomiting) is called an acute abdomen.
Preoperative Concerns
Celiotomy is performed for a variety of reasons; surgery may be indicated for diagnostic
purposes, such as obtaining biopsy samples, or for therapeutic reasons. Many animals
that undergo abdominal exploratory surgery have chronic disease, but in some patients
emergency abdominal surgery must be performed because of acute clinical signs.
Some conditions are life-threatening, such as gastric dilatation- volvulus, colonic
perforation, or severe hemorrhage, and appropriate therapy must be started promptly.
Conditions that require surgery must be differentiated from those that can be managed
medically. Although obviously unnecessary surgery must be avoided, surgery cannot
always be delayed until it is certain the patient will benefit from it.
The decision to operate is based on the history and physical examination findings,
radiographic and ultrasonographic studies, and laboratory analyses. Physical
examination can be unreliable in predicting the severity of abdominal trauma. The
inaccuracy associated with examining patients with acute abdominal disease,
particularly that associated with trauma, can be attributed partly to the patient’s
condition at the time of examination and the delayed development of clinical signs that
occurs with some injuries. Depressed or lethargic animals may not show pain during
abdominal palpation. Clinical signs of hemorrhage often are not apparent immediately
after trauma; delays of 3 to 4 hours between injury and the development of shock and
collapse are common in patients with liver or spleen lacerations. For these reasons,
animals that have suffered traumatic injuries should be closely observed for at least 8 to
12 hours. In most cases life-threatening hemorrhage becomes apparent before this
time. However, animals with traumatic bile peritonitis can show no overt clinical signs for
several weeks. Likewise, traumatic mesenteric avulsion is seldom associated with
clinical signs until peritonitis subsequently develops, usually several days after injury.
Sensitive diagnostic tests such as diagnostic peritoneal lavage may help identify
patients with significant abdominal trauma before overt clinical signs develop.
NOTE ● Be aware that overt clinical signs associated with mesenteric avulsions or
rupture of the biliary tract may not become evident for 1 to 2 weeks after injury.
Preoperative management of most animals undergoing exploratory laparotomy is
dictated by the underlying abdominal disease. General observations include noting the
animal’s attitude and posture, temperature, respiratory rate and effort, and heart rate
and rhythm. Auscultation, percussion, and palpation of the abdomen and a rectal
examination also should be performed. Serial examinations are important to detect
trends or deterioration in the patient’s status. An intravenous catheter should be placed
for fluid and drug administration, and blood samples should be drawn. Useful initial
blood work in an animal with acute abdomen includes hematocrit, serum total protein,
serum glucose concentrations, complete blood count (CBC), platelet count, and blood
urea nitrogen (BUN). Other laboratory tests, such as the serum biochemistry profile and
clotting parameters, can be performed, depending on the animal’s condition and the
suspected underlying disease. Urine may be collected by means of cystocentesis or
catheterization for urinalysis. An indwelling urinary catheter may be used to quantitate
urinary output if necessary. Abdominal radiographs may detect peritoneal fluid (i.e.,
uroabdomen, peritonitis) or abnormal accumulations of air. A recent study determined
that the most common cause of peritoneal effusion in adult cats was neoplasia, whereas
the most common cause in kittens was right-sided heart failure (Wright, Gompf,
DeNovo, 1999). Animals with acute abdominal signs of uncertain cause should have
diagnostic peritoneal lavage if radiographs are nondiagnostic. Electrolyte and hydration
abnormalities should be corrected before surgery.
NOTE ● If you note free air in the abdominal cavity of an animal that has suffered a
recent traumatic injury, consider exploratory surgery; this finding may indicate rupture or
perforation of the gastrointestinal tract.
Anesthetic Considerations
The anesthetic management of animals with abdominal disease depends on the
underlying disease. Young, healthy animals can be premedicated with an
anticholinergic and opioid (i.e., oxymorphone, butorphanol, buprenorphine) and induced
with thiopental, propofol, or a combination of diazepam and ketamine given
intravenously to effect.
Antibiotics
The appropriate use of antibiotics in patients undergoing abdominal surgery depends on
the underlying disease, the animal’s overall general health, and the length and type of
surgical procedure. Surgeries of less than 1½ to 2 hours in which a contaminated,
hollow viscus is not opened do not usually warrant prophylactic antibiotics.
Surgical Anatomy
The rectus sheath is composed of an external and internal leaf. The external leaf is
formed by the aponeurosis of the external abdominal oblique muscle and a portion of
the aponeurosis of the internal abdominal oblique muscle. The aponeurosis of the
transversus abdominis muscle joins the external leaf near the pubis. The internal leaf
consists of a portion of the aponeurosis of the internal abdominal oblique muscle, the
aponeurosis of the transversus abdominis muscle, and the transversalis fascia. The
internal leaf disappears in the caudal third of the abdomen where the aponeurosis of the
internal abdominal oblique muscle joins the external leaf, leaving the caudal rectus
abdominis muscle covered only by a thin sheet of transversalis fascia and peritoneum.
NOTE ● The linea alba is easier to locate near the umbilicus because it becomes
narrower near the pubis.
Surgical Techniques
The abdomen generally is explored by means of a ventral midline incision. In most
animals the entire abdomen, including the inguinal areas, and the caudal thorax should
be prepared for aseptic surgery to allow extension of the incision into the thoracic or
pelvic cavities if necessary. Prepping too small an area is a common mistake,
particularly for abdominal exploration in trauma patients. To visualize all abdominal
structures adequately, the incision must extend from the xiphoid process to the pubis. If
only a specific abdominal structure is to be examined, a shorter incision can be made. A
caudal abdominal incision that extends from the umbilicus to the pubis is adequate for
bladder exploration; similarly, a cranial abdominal incision (i.e., umbilicus to xiphoid
process) allows evaluation of the liver and stomach. Rarely, the midline incision is
extended laterally at the xiphoid process (1 cm caudal to the last rib) to facilitate
exposure of the liver, biliary system, and diaphragm. A paracostal (paralumbar)
celiotomy can be used to expose the kidneys and adrenal glands; it is most commonly
used for unilateral adrenalectomy.
NOTE ● Always count surgical sponges before making the incision and before
abdominal closure to help ensure that none are inadvertently left in the abdominal
cavity.
Ventral Midline Celiotomy in Cats and Female Dogs
With the patient in dorsal recumbency, make a ventral midline skin incision beginning
near the xiphoid process and extending caudally to the pubis. Sharply incise the
subcutaneous tissues until the external fascia of the rectus abdominis muscle is
exposed. Ligate or cauterize small subcutaneous bleeders and identify the linea alba.
Tent the abdominal wall and make a sharp incision into the linea alba with a scalpel
blade. Palpate the interior surface of the linea for adhesions. Use scissors to extend the
incision cranially or caudally (or both) to near the extent of the skin incision. Digitally
break down the attachments of one side of the falciform ligament to the body wall or
excise it and remove it entirely if it interferes with visualization of cranial abdominal
structures. Clamp the cranial end of the falciform ligament and ligate or cauterize
bleeders before removing it.
Ventral Midline Celiotomy in male Dogs
With the patient in dorsal recumbency, place a towel clamp on the prepuce and clamp it
to the skin on one side of the body. Drape the tip of the prepuce and clamp outside the
surgical field. Make a ventral midline skin incision beginning at the xiphoid process and
continuing caudally to the prepuce. Curve the incision to the left or right of the penis and
prepuce (i.e., the side opposite the clamped prepuce) and extend it to the level of the
pubis. Incise the subcutaneous tissues and fibers of the preputialis muscle to the level
of the rectus fascia in the same plane as the skin incision. Ligate or cauterize large
branches of the caudal superficial epigastric vein at the cranial aspect of the prepuce.
Retract incised skin and subcutaneous tissues laterally and locate the linea alba and
external fascia of the rectus abdominis muscle. Do not attempt to locate the caudal linea
alba until subcutaneous tissues have been incised and the abdominal musculature
fascia identified. Tent the abdominal wall and make a sharp incision into the linea alba
with a scalpel blade. Palpate the interior surface of the linea for adhesions. Use scissors
to extend the incision cranially or caudally (or both) to near the extent of the skin
incision.
Paracostal Celiotomy
Position the animal in lateral recumbency and place a rolled towel or sandbag between
the animal and the operating table. Make a skin incision from the ventral vertebral
column to near the ventral midline. Center the incision halfway between the wing of the
ilium and the last rib. Extend the incision through the external abdominal oblique muscle
with scissors. Separate internal abdominal oblique and transversus abdominis muscle
fibers and expose the peritoneal and transversalis fascia. Tent the peritoneum and
sharply incise it with scissors.
Abdominal Exploration
Systematically explore the entire abdomen.
Various techniques may be used; however, every surgeon should develop a consistent
pattern to ensure that the entire abdominal cavity and all structures are visualized
and/or palpated in each animal.
Use moistened laparotomy sponges to protect tissues from drying during the procedure.
If generalized infection is present or if diffuse intraoperative contamination has occurred,
flush the abdomen with copious amounts of warmed, sterile saline solution.
Historically, many different antiseptics (i.e., povidoneiodine, chlorhexidine) and
antibiotics have been added to lavage fluids. Povidone-iodine is the most widely used
antiseptic; however, this practice has not shown a beneficial effect in repeated
experimental and clinical trials and may be detrimental in animals with established
peritonitis because the carrier, polyvinylpyrrolidone, inhibits macrophage chemotaxis.
Similarly, there is no substantial evidence that adding antibiotics to lavage fluid benefits
patients treated with appropriate systemic antibiotics.
Remove the lavage fluid and blood and inspect the abdominal cavity before closure to
ensure that all foreign material and surgical equipment have been removed. Perform a
sponge count and compare it with the preoperative count to ensure that surgical
sponges have not been left in the abdominal cavity.
Abdominal Wall Closure
The linea alba may be closed with a simple continuous or a simple interrupted suture
pattern. The simple continuous technique does not increase the risk of dehiscence
when properly performed (i.e., secure knots, appropriate suture material, adequate bites
in the rectus sheath), and it allows for rapid closure. Preferably strong, absorbable
suture material (i.e., polydioxanone, polyglyconate, poliglecaprone 25) should be used
for continuous suture patterns, and six to eight knots should be placed at each end of
the incision line. Surgical gut and stainless steel wire should not be used for continuous
suture patterns.
On each side of the incision, incorporate 4 to 5 mm of fascia in each suture. Place
interrupted sutures no further apart than 3 to 5 mm, depending on the animal’s size.
Tighten sutures sufficiently to appose but not enough to strangulate tissue, because
sutures that strangulate tissue negatively affect wound healing. Incorporate full
thickness bites of the abdominal wall in the sutures if the incision is midline (i.e., through
the linea alba). Do not incorporate the falciform ligament between the fascial edges. If
the incision is lateral to the linea alba and muscular tissue is exposed (i.e., paramedian
incision), close the external rectus sheath without including muscle or peritoneum in the
sutures. Close subcutaneous tissues with a simple continuous pattern of absorbable
suture material and reappose the preputialis muscle fibers in the male dog. Use
nonabsorbable sutures (simple interrupted or continuous appositional pattern) or
stainless steel staples to close skin. Place skin sutures without tension.
For paracostal celiotomy, close the individual muscle layers with synthetic absorbable
suture material in a continuous or interrupted pattern. Attempt to eliminate dead space
between muscle layers. Appose subcutaneous tissue with absorbable suture in a
continuous or interrupted pattern and close the skin with nonabsorbable suture in a
simple interrupted or continuous pattern.
Healing of the Abdominal Wall
The ability of tissues to hold sutures without tearing depends on the tissue’s strength
(collagen density) and the orientation of collagen fibrils. Skin and fascia are strong,
whereas muscle and fat are weak. Peritoneum heals rapidly across the incision and
does not contribute to wound strength, therefore closure of this layer is not beneficial.
Experimental and clinical studies in dogs suggest that suturing peritoneum may
increase the incidence of postoperative intraabdominal adhesions.
NOTE ● Make sure to incorporate fascia in the linea closure. Because the holding
layer of abdominal incisions is collagen dense fascia rather than muscle, dehiscence is
common if the rectus fascia is not incorporated in sutures.
SUTURE MATERIALS AND SPECIAL INSTRUMENTS
Useful instruments for celiotomy include Balfour abdominal retractors, Poole or
Yankauer suction tips, malleable retractors, and Mixter (right-angle) forceps.
Laparotomy pads and 4 × 4 sponges should have radiopaque markers.
Postoperative Care and Assessment
The abdominal incision should be checked twice daily for redness, swelling, or
discharge. If the animal licks or chews at the incision, an Elizabethan collar or sidebar
should be used to prevent iatrogenic suture removal. Early signs of altered wound
healing are inflammation and edema. Serosanguineous drainage from the incision and
swelling are consistent signs of acute incisional dehiscence. Dehiscence usually occurs
3 to 5 days after surgery, when minimal healing has occurred and the sutures have
weakened; however, it may occur earlier if knots were tied improperly or if fascia was
not incorporated into the sutures. Evisceration usually results in sepsis and severe
blood loss secondary to mutilation of exposed intestine and must be treated promptly.
The abdomen should be bandaged, fluid therapy initiated, and broad-spectrum
antibiotics given while the animal is prepared for surgery. If technical failure is
suspected, such as poor knot tying or improper suturing, the entire suture line should be
removed and replaced. Debridement of the wound edges is unnecessary and delays
wound healing. The intestine should be closely inspected for viability and damaged
sections resected if appropriate. The abdominal cavity should be lavaged copiously with
warmed, sterile saline. Open abdominal drainage should be considered in animals with
generalized peritonitis. Wound disruption after 10 to 21 days usually results in hernia
formation rather than evisceration. Hernial repair in these animals may require excision
of fibrotic tissues. Subsequent closure requires that tissue layers be accurately
apposed.
Complications
Dehiscence (incisional hernias) may occur if improper surgical technique is used (see
the above discussion). The most common causes of wound dehiscence in the early
postoperative period are suture breakage, knot slippage or untying, or sutures cutting
through tissue. A higher rate of dehiscence may be seen in animals with wound
infections, fluid or electrolyte imbalances, anemia, hypoproteinemia, metabolic disease,
immunosuppression (e.g., feline immunodeficiency virus [FIV], feline leukemia virus), or
abdominal distention or in those that have been treated with corticosteroids,
chemotherapeutic agents, or radiation. Suture sinus formation has been reported with
nonabsorbable suture material. Such cases require surgical resection of affected
tissues and removal of offending sutures.
Special Age Considerations
Healing may be delayed in debilitated, very young or very old, or hypoproteinemic
animals; chromic gut suture should not be used for abdominal wall closure in these
patients.
References
Wright KN, Gompf RE, DeNovo RC: Peritoneal effusion in cats: 65 cases (1981-1997),
J Am Vet Med Assoc 214:375, 1999.
Suggested reading
Brady CA et al: Severe sepsis in cats: 29 cases (1986-1998), J Am Vet Med Assoc
217:531, 2000.
Hosgood G, Pechman RD, Casey HW: Suture sinus in the linea alba of two dogs, J
Small Anim Pract 33:285, 1992.
Wess G, Reusch C: Evaluation of five portable blood glucose meters for use in dogs, J
Am Vet Med Assoc 216:203, 2000.
TRAUMATIC ABDOMINAL WALL HERNIAS
Definitions
External abdominal hernias are defects in the external wall of the abdomen that allow
protrusion of abdominal contents; internal abdominal hernias are those that occur
through a ring of tissue confined within the abdomen or thorax (i.e., diaphragmatic
hernia, hiatal hernia). External abdominal hernias may involve the abdominal wall
anywhere other than the umbilicus, inguinal ring, femoral canal, or scrotum.
Synonyms
Abdominal hernias may be defined according to their location (i.e., ventral, prepubic,
subcostal, hypochondral, paracostal, or lateral). The cranial pubic ligament formerly was
called the prepubic tendon.
General Considerations and Clinically Relevant Pathophysiology
Abdominal hernias generally occur secondary to trauma, such as vehicular accidents or
bite wounds; however, they occasionally have been reported as congenital lesions.
Congenital cranial abdominal hernias (i.e., cranial to the umbilicus) have been reported
in association with peritoneopericardial diaphragmatic hernias in dogs and cats.
Abdominal hernias are false hernias because they do not contain a hernial sac. When
associated with blunt trauma, they arise as a result of rupture of the wall from within
caused by an increase in intraabdominal pressure while the abdominal muscles are
contracted. The most common sites for traumatic abdominal hernias are the prepubic
region and the flank. Cranial pubic ligament hernias often occur in association with
pubic fractures. Paracostal hernias may result in migration of abdominal contents along
the thoracic wall. In rare cases the abdominal contents enter the chest through defects
in the intercostal muscles.
Diagnosis
Clinical Presentation
Signalment. Most animals with abdominal hernias are young.
History. A history of trauma is common with abdominal hernias. The hernia initially
may be overlooked while more obvious or life-threatening injuries are treated. If
strangulation or intestinal obstruction occurs, the animal may be presented for treatment
of vomiting, abdominal pain, anorexia, and/or depression.
Physical Examination Findings
Abdominal structures (i.e., organs or omentum) in the subcutaneous space or between
muscle layers usually cause asymmetry of the abdominal contour. The size of the
swelling may not correspond to the size of the hernia, particularly if intestine has
migrated into the hernia. The swelling should be palpated carefully to discern the
contents of the hernia (i.e., intestine, bladder, or spleen) and to locate the abdominal
defect. These patients should be thoroughly examined to determine whether a
concurrent abdominal or thoracic injury or abnormality exists. Rupture of the cranial
pubic ligament often is difficult to palpate because of subcutaneous swelling and pain.
Radiography and Ultrasonography
Radiographs should be taken in animals with abdominal hernias. Routine ventral dorsal
and lateral views may show an associated abdominal or thoracic injury (e.g., abdominal
fluid, diaphragmatic hernia). Abdominal radiographs may help confirm the presence of a
hernia (i.e., subcutaneous intestinal loops and loss of the ventral abdominal stripe)
when the abdominal wall defect cannot be palpated because of swelling or pain.
Ultrasound scans may also help define the contents of hernias.
Laboratory Findings
Abnormalities associated with abdominal hernias vary depending on the severity of
concurrent internal injuries.
Differential Diagnosis
Most hernias are diagnosed on physical examination. Differential diagnoses for
abdominal swellings include abscesses, cellulitis, hematomas or seromas, and
neoplasia.
Medical Management
Initial treatment of animals with abdominal hernias is directed toward diagnosing and
treating shock and concurrent life-threatening internal injuries.
Surgical Treatment
Patients that sustain a traumatic injury severe enough to cause an abdominal hernia or
patients that sustain penetrating abdominal wounds (i.e., gunshot, bite wounds) should
have a xyphoid to pubis abdominal exploratory laparotomy. All visceral structures
should be carefully examined to signs of trauma (e.g., mesenteric rents, ruptured hollow
viscous organs, avulsed kidney, ureteral damage). In addition, abdominal ceiliotomy
approach facilitates abdominal hernia closure. Most abdominal hernias can be repaired
by suturing torn muscle edges or apposing the disrupted abdominal wall edge to the
pubis, ribs, or adjacent fascia. In rare cases synthetic mesh must be used to repair the
defect. Some hernias (i.e., intestinal strangulation, urinary obstruction, concurrent organ
trauma) require emergency surgical correction. However, the extent of devitalized
muscle may not be apparent initially, and in patients in stable condition, delaying
surgery until muscle damage can be accurately assessed facilitates surgical correction.
The most common complications of surgery are hernia recurrence and wound infection.
Abdominal hernias that occur secondary to bite wounds usually are contaminated;
wound infection and dehiscence of the skin or hernial repair (or both) may occur. Mesh
should not be placed in these hernias, hernial closure is performed during exploratory
laparotomy, and the skin wounds should be left open to drain. Treatment of infected
wounds includes cultures, drainage, antibiotics, and/or flushing.
Preoperative Management
Preoperative care depends on the animal’s status and concurrent injuries. Hydration
and electrolyte abnormalities should be corrected before surgery.
Anesthesia
If there are no concurrent abdominal injuries or disease, a variety of anesthetic
protocols can be used to anesthetize the animal. However, the presence of underlying
disease may dictate the anesthetic management of sick or debilitated patients.
Surgical Anatomy
The abdominal wall is composed of four muscle layers (the external and internal
abdominal oblique muscles, the rectus abdominis muscle, and the transversus
abdominis muscle). Abdominal hernias may occur at insertions or attachments of these
muscles or through muscle bellies themselves. The cranial pubic ligament (prepubic
tendon) is a band of transverse fibers that connects the iliopectineal eminence and
pectineal muscle origin of one side with those on the other side. This ligament attaches
the rectus abdominis muscle to the pelvis.
Positioning
For ventral hernias the animal is placed in dorsal recumbency and the area around the
hernia is prepared for aseptic surgery. Repair of ruptures of the cranial pubic ligament
may be facilitated by placing the animal in dorsal recumbency with the rear limbs flexed
and pulled cranially.
Surgical Techniques
Abdominal Hernias
For most abdominal hernias, perform a ventral midline abdominal incision to allow the
entire abdomen to be explored. Assess the extent of visceral herniation. Reduce the
herniated contents and amputate or excise necrotic or devitalized tissue around the
hernia. Close the muscle layers of the hernia with simple interrupted or simple
continuous sutures. If a large area of devitalized tissue is removed, use synthetic mesh
such as Marlex or Prolene to close the defect (do not place mesh in infected sites). Fold
the edges of the mesh over and suture the folded edges to viable tissue using simple
interrupted sutures. Injuries to the cranial pubic ligament can be difficult to repair. If
necessary, drill holes in the pubic bone to anchor the sutures.
Paracostal hernias. Make a midline abdominal incision. Explore the hernia and suture
the torn edges of the transverse, internal, and external abdominal oblique muscles.
Incorporate a rib in the suture if muscle has been avulsed from the costal arch.
Cranial pubic ligament hernias. Make a ventral midline skin incision and identify the
ruptured tendon and its pubic insertion. Evaluate the inguinal rings and vascular lacuna;
these hernias may extend into the femoral region as a result of rupture of the inguinal
ligament. Reattach the free edge of the abdominal wall to the cranial pubic ligament with
simple interrupted sutures. As an alternative, suture the tendon remnant to the muscle
fascia and periosteum covering the pubis or anchor it to the pubis by drilling holes in the
pubic bone through which sutures can be placed. If the hernia extends into the femoral
region, it may be necessary to suture the body wall to the medial fascia of the adductor
muscles. When doing so, take care to avoid damaging the femoral vessels or nerves.
Suture Materials and Special Instruments
Strong, absorbable suture (polydioxanone, polyglyconate, poliglecaprone 25) or
nonabsorbable suture (polypropylene or nylon) should be used to repair abdominal or
ventral hernias. Marlex and Prolene synthetic mesh may be used to repair some large
defects.
Postoperative Care and Assessment
The postoperative care of these patients is dictated by the presence of concurrent
injuries or disease. The patient should be kept quiet, and the wound should be checked
frequently for infection or dehiscence. Vomiting, fever, and/or leukocytosis may indicate
peritonitis.
Prognosis
The prognosis generally is good, and recurrence is uncommon. When recurrence
occurs, it generally is noted within a few days of surgery. Most animals have excellent
long-term results when appropriate techniques are used.
Suggested reading
Waldron DR, Hedlund CS, Pechman R: Abdominal hernias in dogs and cats: a review of
24 cases, J Am Anim Hosp Assoc 22:817, 1986.
PERITONITIS
DEFINITION
Primary generalized peritonitis refers to spontaneous inflammation of the peritoneum
without any preexisting intraabdominal pathologic condition. Secondary generalized
peritonitis occurs in conjunction with an intraabdominal pathologic condition and may
be further classified as infectious or noninfectious.
General Considerations and Clinically Relevant Pathophysiology
Secondary generalized peritonitis is the predominant form of peritonitis in dogs and
usually is caused by bacteria. Most cases arise through contamination from the
gastrointestinal tract, often as a result of surgical wound dehiscence (Swann, Hughes,
2000). Other causes include gallbladder perforation, rupture, or necrosis; gastric or
intestinal foreign bodies; intussusception; mesenteric avulsion; gastric dilatationvolvulus; necrotizing cholecystitis; pancreatic abscessation; prostatic abscesses; or
foreign body penetration of the body wall. Primary generalized peritonitis occurs in cats
and is associated with feline infectious peritonitis.
Diagnosis
Clinical Presentation
Signalment. Any age, gender, or breed of dog or cat may develop peritonitis. It is
particularly common in young animals that have perforating foreign bodies and in those
that suffer abdominal injury, such as vehicular trauma or bite wounds.
History. The history often is nonspecific. The animal may not show signs of illness for
several days after the traumatic episode. Mesenteric avulsions often do not cause
clinical signs of peritonitis for 5 to 7 days after the injury. Animals with traumatic bile
peritonitis may be asymptomatic for several weeks after the injury. Most animals are
presented for treatment of lethargy, anorexia, vomiting, diarrhea, and/or abdominal pain.
NOTE ● Be sure to evaluate any sick intact female dog for pyometra.
Physical Examination Findings
Abdominal palpation usually causes pain in affected animals. The pain may be
localized, but generalized pain is more common, and the animal often tenses or “splints”
the abdomen during palpation. Vomiting and diarrhea may be noted. Abdominal
distension may be noted if sufficient fluid has accumulated. Pale mucous membranes,
prolonged capillary refill times, and tachycardia may indicate that the animal is in shock.
Dehydration and arrhythmias may also occur.
Radiography and Ultrasonography
The classic radiographic finding in animals with peritonitis is loss of abdominal detail
with a focal or generalized “ground glass” appearance. The intestinal tract may be
dilated with air or fluid or both. Free air in the abdomen may be noted with rupture of a
hollow organ; it also sometimes occurs without gut rupture as a result of gasproducing
anaerobes. A more localized peritonitis may occur secondary to pancreatitis and can
cause the duodenum to appear fixed and elevated. Ultrasonography is useful for
localizing fluid accumulation and helping to determine the etiology.
Laboratory Findings
The most common laboratory finding in animals with peritonitis is a marked
leukocytosis; however, the neutrophil count may be normal or low in some cases. The
predominant cell type is the neutrophil, and a left shift is often but not always apparent.
Other abnormalities may include anemia, dehydration, and electrolyte and acid-base
abnormalities.
In early cases of peritonitis little or no abdominal effusion may be seen. When effusion
is present, abdominocentesis should be performed and fluid retrieved for analysis.
Inflammatory fluids should have an elevated number of neutrophils, which may appear
degenerative. Significant numbers of leukocytes accumulate in the peritoneal cavity
within 2 to 3 hours of contamination with blood, bile, urine, feces, or gastric or
pancreatic secretions. Leukocyte counts in the abdominal fluid of normal dogs usually
are less than 500 cells/µl. In specimens obtained by peritoneal lavage in dogs, white
blood cell (WBC) counts of 1000 to 2000 cells/µl indicate mild to moderate irritation;
counts over 2000 cells/µl indicate marked peritonitis (Hardie, 1995). The presence of
degenerate leukocytes and bacteria in the lavage fluid also suggests intraabdominal
infection. However, the presence and number of WBCs should be correlated with other
clinical findings when considering abdominal exploration. Elevated leukocyte counts are
found in most dogs after abdominal surgery. In animals that have undergone recent
surgery, 7000 to 9000 cells/µl indicates mild to moderate peritonitis, and more than
9000 cells/µl indicates marked peritonitis (Hardie, 1995). An abdominal effusion glucose
concentration below 50 mg/dl may be a specific indicator of bacterial peritonitis in dogs
(Swann, Hughes, 2000).
After abdominocentesis the amount of blood in the abdominal cavity can be estimated
by observing the lavage sample. A red color reflects the presence of red blood cells
(RBCs), and a deep red color usually indicates severe hemorrhage. If newsprint cannot
be read through the plastic tubing, hemorrhage is significant; if print can be seen
through the tubing, only moderate or minimal hemorrhage is present. The amount of
blood in the abdominal cavity can be estimated using the equation shown below:
TABLE Estimating the Amount of Blood in Abdominal Fluid
The amount of blood in the abdominal cavity can be estimated using the following
formula:
LV
X
P-L
where:
X = Amount of blood in the abdominal cavity
L = Packed cell volume (PCV) of the returned lavage fluid
V = Volume of lavage fluid infused into the abdominal cavity
P = PCV of the peripheral blood before intravenous infusion of fluids
Surgical intervention may be indicated when the packed cell volume (PCV) of lavage
samples taken within 5 to 20 minutes of each other increases substantially or if an
animal in shock does not respond to appropriate fluid therapy.
Differential Diagnosis
Advanced peritonitis with significant accumulation of abdominal fluid is not difficult to
diagnose. The difficulty usually arises in determining the etiology of the effusion or
infection. Early peritonitis, before the onset of overt clinical signs, is difficult to diagnose
and may require diagnostic peritoneal lavage.
Medical Management
The goals of management of animals with peritonitis are to identify the source of
peritonitis, control the source of peritonitis, lavage the peritoneal cavity, provide an
efficient means of peritoneal drainage if necessary, resolve the infection, and restore
normal fluid and electrolyte balances. Food should be withheld if the animal is vomiting.
Intravenous fluid replacement therapy should be initiated as soon as possible,
particularly if the animal is dehydrated or appears to be in shock (in dogs, 60 to 90
ml/kg/hour; in cats, 40 to 60 ml/kg/hour). Synthetic colloids such as hetastarch and
dextran 70 may be beneficial, particularly if vasculitis is present. Hypokalemia and
hyponatremia may be present and require intravenous supplementation. Hypoglycemia
is common if the animal has septic shock (systemic inflammatory response syndrome),
and glucose may need to be added to the fluids (i.e., 2.5% to 5% dextrose). Standard
shock therapy should be initiated (i.e., fluid replacement and antibiotics, with or without
soluble corticosteroids). If severe metabolic acidosis is present, bicarbonate therapy
may be indicated.
Broad-spectrum antibiotic therapy should be initiated as soon as the diagnosis is made.
Escherichia coli, Clostridium spp., and Enterococcus spp. are commonly isolated from
animals with peritonitis, and ampicillin plus enrofloxacin typically is an effective
antimicrobial combination. However, amikacin sulfate plus clindamycin or amikacin
sulfate plus metronidazole may be necessary for some anaerobic infections. A second
generation cephalosporin, such as cefoxitin sodium, may also be used if gram-negative
plus anaerobic infection is suspected. If renal compromise is present in an animal with a
resistant bacterial infection, imipenem may be considered. The initial antibiotic therapy
should be altered according to the aerobic and anaerobic culture results of lavage fluid
or cultures obtained at surgery.
Low-dose heparin increases survival and significantly reduces abscess formation in
experimental peritonitis. The inflammatory process in peritonitis is associated with an
outpouring of fibrous exudate that causes intraabdominal loculation of bacteria. The
loculated bacteria are protected from host defense mechanisms and antibiotics that may
not be able to penetrate the fibrin clots. Although the exact mechanism of its beneficial
effect is still unknown, there appears to be little doubt that heparin is indicated in
patients with severe peritonitis. Heparin may also be incubated with plasma and given
to animals with disseminated intravascular coagulation (DIC).
Surgical Treatment
Abdominocentesis (see below) is the percutaneous removal of fluid from the abdominal
cavity, usually for diagnostic purposes, although it may occasionally be therapeutic.
Indications include shock without apparent cause, undiagnosed disease with signs
involving the abdominal cavity, suspicion of postoperative gastrointestinal dehiscence,
blunt or penetrating abdominal injuries (i.e., gunshot wounds, dog bites, vehicular
injury), and undiagnosed abdominal pain. A multifenestrated catheter should be used to
enhance fluid collection. Physical and radiographic examinations should precede
abdominocentesis to rule out instances in which it may not be safe and to guide needle
placement. Four-quadrant paracentesis may be performed if simple abdominocentesis
is not successful in retrieving fluid. It is similar to simple abdominocentesis except that
multiple abdominal sites are assessed by dividing the abdomen into four quadrants
through the umbilicus and tapping each of these four areas. Diagnostic peritoneal
lavage should be performed in animals suspected of having peritonitis if the above
methods are unsuccessful in obtaining fluid for analysis.
Exploratory surgery is indicated when the cause of peritonitis cannot be determined or
when bowel rupture, intestinal obstruction (e.g., bowel incarceration, neoplasia), or
mesenteric avulsion is suspected. Serosal patching and plication reduce the incidence
of intestinal leakage, dehiscence, or repeated intussusception. Animals that require
surgery and that have peritonitis secondary to intestinal trauma (disruption of
mesenteric blood supply, bowel perforation, chronic intussusception, foreign body) often
are hypoproteinemic. The role that protein levels play in healing intestinal incisions is
not well understood. However, most surgeons are concerned that hypoproteinemic
patients may not heal as quickly as patients with normal protein levels, despite one
study that showed similar complication rates among animals with normal protein levels
and those that were hypoproteinemic and undergoing intestinal surgery (Harvey, 1990).
Most experimental evidence has shown that retardation of wound healing is not seen
with moderate protein depletion but only with severe deficiencies (less than 1.5 to 2
g/dl).
Although the practice of lavaging the abdominal cavity of animals with peritonitis is
controversial, lavage generally is indicated with diffuse peritonitis. Lavage should be
done with care in animals with localized peritonitis to avoid dissemination of infection.
When lavage is performed, as much of the fluid as possible should be removed,
because fluid inhibits the body’s ability to fight off infection, probably by inhibiting
neutrophil function. Historically, many different agents have been added to lavage fluids,
especially antiseptics and antibiotics. Povidone-iodine is the most widely added
antiseptic; however, its use may be contraindicated with established peritonitis.
Furthermore, no beneficial effect of this agent has been shown in repeated experimental
and clinical trials in animals. Although a great many antibiotics have been added to
lavage fluids over the years, there is no substantial evidence that their addition is of any
benefit to patients who are being treated with appropriate systemic antibiotics. Warmed
sterile physiologic saline is the most appropriate lavage fluid.
Open abdominal drainage (OAD) is a useful technique for managing animals with
peritonitis. Reported advantages include improvement in the patient’s metabolic
condition secondary to improved drainage, less formation of abdominal adhesions and
abscesses, and access for repeated inspection and exploration of the abdomen. With
this technique the abdomen is left open, and sterile wraps are placed around the
wound. The frequency of wrap changes depends on the amount of fluid drained and the
amount of external soiling. Complications of open abdominal drainage include persistent
fluid loss, hypoalbuminemia, weight loss, adhesion of abdominal viscera to the
bandage, and contamination of the peritoneal cavity with cutaneous organisms.
There is evidence to suggest the use of Jackson Pratt drains are an efficient means of
draining the peritoneal cavity for 2 to 4 days post operatively. This technique allows the
surgeon to perform a primary abdominal closure yet still provide abdominal drainage.
Preoperative Management
Animals with peritonitis that are in shock should be stabilized before surgery.
Preoperative management of peritonitis is similar to that described in the previous
discussion on medical management. The nutritional management of animals with
peritonitis is extremely important; if the patient is debilitated, vomiting, or unlikely to
resume eating for several days after surgery, enteral or parenteral hyperalimentation
should be considered.
Anesthesia
Animals with peritonitis often are endotoxic or hypotensive or both. Small amounts of
endotoxins are normally absorbed from the intestine and transported via the portal
system to the liver, where they are removed and destroyed by hepatocytes.
Hypotension in dogs is associated with intense portal vasoconstriction. This
vasoconstriction causes breakdown of the intestinal mucosal barrier, allowing more
endotoxin to be absorbed from the intestines. If hepatic function is impaired, a common
condition in septic animals, small doses of endotoxin that normally would be harmless
may be lethal. For these reasons, hypotension should be corrected before and
prevented during and after surgery in animals with peritonitis. Animals with a total
protein level under 4 g/dl or an albumin level under 1.5 g/dl may benefit from
perioperative colloid administration. Colloids may be given preoperatively,
intraoperatively, or postoperatively (or all three) for a total dose of 20 ml/kg/day. If
colloids are given during surgery (7 to 10 ml/kg), acute intraoperative hypotension
should be treated with crystalloids.
Dobutamine or dopamine may be given during surgery for inotropic support.
Dobutamine is less arrhythmogenic and chronotropic than dopamine and is preferred if
the patient is hypotensive and anuric. If the patient is anuric and normotensive, lowdose dopamine (0.5 to 1.5 µg/kg/minute given intravenously) plus furosemide (0.2
mg/kg given intravenously) may be preferable. These patients should be monitored for
arrhythmias or tachycardia.
Hepatic necrosis occurs during sepsis and reduces liver function. The pathogenesis of
hepatic necrosis is uncertain, but the condition may be caused by hypotension and
hypoxia. Patients with hepatic necrosis may have a diminished ability to metabolize
drugs, and prolonged duration of action or altered function of drugs may result.
Acepromazine should not be used in animals with peritonitis if severe hepatic
dysfunction is suspected. Diazepam plus an opioid is a useful premedicant in patients
with hepatic dysfunction. Diazepam used alone may disinhibit some behaviors, and it
should be used with caution in hypoalbuminemic patients. Most opioids have little or no
adverse effect on the liver; however, morphine should not be given intravenously to
dogs with hepatic dysfunction because it may cause hepatic congestion as a result of
histamine release and hepatic vein spasm. Although some opioid analgesics may have
prolonged action when hepatic function is reduced, their effects can be antagonized.
Barbiturates (e.g., thiopental) should be used cautiously or avoided in patients with
significant hepatic dysfunction. An anticholinergic may be given if the animal is
bradycardic.
Etomidate should be used with caution in animals with renal insufficiency, because a
single induction dose of this agent has caused hemolysis in dogs and cats. The benefit
of cardiovascular stability should be weighed against this risk when etomidate is used.
The drug should not be used in animals with adrenal insufficiency (Pablo, Bailey, 1999).
Positioning
For abdominocentesis and diagnostic lavage, the abdomen should be clipped and
prepared aseptically. These procedures may be performed with the animal in lateral
recumbency or standing.
Surgical Techniques
Abdominocentesis
Insert an 18- or 20-gauge, 1½ -inch plastic over-the-needle catheter (with added side
holes) into the abdominal cavity at the most dependent part of the abdomen. Do not
attach a syringe; instead allow the fluid to drip from the needle and collect in a sterile
tube. If sufficient fluid is obtained, place it in a clot tube and an ethylenediamine
tetraacetic acid (EDTA) tube, submit samples for aerobic and anaerobic culture, and
make four to six smears for analysis. If fluid is not obtained, apply gentle suction using a
3-ml syringe.
It is difficult to puncture bowel by this method, because mobile loops of bowel move
away from the tip of the needle as it strikes them. Perforations created by a needle this
size usually heal without complications. The major disadvantage of needle paracentesis
is that it is insensitive to the presence of the small volumes of intraperitoneal fluid and
thus a negative result can be meaningless. At least 5 to 6 ml of fluid per kilogram of
body weight must be present in the abdominal cavity of dogs to obtain positive results in
most cases using this technique.
Diagnostic Peritoneal Lavage
Make a 2-cm skin incision just caudal to the umbilicus and ligate any bleeders to avoid
false positive results. Spread loose subcutaneous tissues and make a small incision in
the linea alba. Hold the edges of the incision with forceps while the peritoneal lavage
catheter (Stylocath) without the trocar is inserted into the abdominal cavity. Direct the
catheter caudally into the pelvis. With the catheter in place, apply gentle suction. If
blood or fluid cannot be aspirated, connect the catheter to a bottle of warm sterile saline
and infuse 20 ml/kg of fluid into the abdominal cavity. When the calculated volume of
fluid has been delivered, roll the patient gently from side to side, place the bottle on the
floor, vent it, and collect the fluid by gravity drainage. Do not be surprised if you do not
retrieve all of the fluid, particularly in dehydrated animals.
Exploratory Laparotomy
Perform a ventral midline incision from the xiphoid process to the pubis. Obtain a
sample of fluid for culture and analysis. Explore and inspect the entire abdomen. Find
the source of infection and correct it. Break down adhesions that may hinder drainage.
Lavage the abdomen with copious amounts of warm, sterile saline if the infection is
generalized. Remove as much necrotic debris and fluid as possible. Close the abdomen
routinely, place an abdominal drain, or perform open abdominal drainage.
Open Abdominal Drainage
After completing the abdominal procedure, leave a portion of the abdominal incision
(usually the most dependent portion) open to drain. Generally, make the opening just
large enough to allow a gloved hand to be inserted. Close the cranial and caudal
aspects of the incision with monofilament suture using a continuous suture pattern.
Place a sterile laparotomy pad over the opening, then place a sterile wrap over the
laparotomy pad. Change the wrap at least twice daily initially with the animal standing;
sedation is seldom necessary (use sterile bandage materials and wear sterile gloves).
The volume of drainage dictates the number of wrap changes needed. Break down
adhesions to the incision that may interfere with drainage. Abdominal lavage may be
attempted but is seldom necessary. Place a diaper over the wrap to reduce
contamination from urine. Assess the fluid daily for bacterial numbers and cell
morphology. When the bacterial numbers have declined and the neutrophil morphology
is normal (nondegenerative), close the incision (generally in 3 to 5 days). If the opening
is small, it may be left to heal by second intention.
Suture Materials and Special Instruments
Monofilament synthetic nonabsorbable suture (polypropylene or nylon) or slowly
absorbable suture (polydioxanone or polyglyconate) should be used to close the
abdomen in animals with peritonitis. Braided suture (Dacron, silk, braided nylon) or
suture that may be rapidly degraded (chromic gut) should not be used.
Postoperative Care and Assessment
Fluid therapy should be continued postoperatively in most animals with peritonitis and is
mandatory in those being managed with an open abdomen. Electrolytes, acid-base, and
serum protein should be assessed in the postoperative period and corrected as
necessary. Nasal oxygen may benefit septic animals. Ensuring that patients with
peritonitis have an adequate caloric intake postoperatively often is difficult. An animal’s
energy requirement is much greater after injury or illness than at rest. Generally, the
formula [30 × Weight (kg)] 1 + 70 is used to calculate a resting animal’s energy
requirement. Postoperatively, the metabolic rate of dogs and cats increases 25% to
35% over resting levels. With mild trauma the increase in the energy requirement is
35% to 50%; with sepsis 50% to 70% more calories are required. The factor 1.5 has
been used to estimate the energy requirement of ill or injured dogs and cats. Meeting
these caloric requirements in dogs with intestinal disease is particularly difficult and may
require enteral or parenteral nutritional support. If hypoproteinemia becomes severe,
plasma transfusions should be considered.
Prognosis
The prognosis for animals with generalized peritonitis is guarded; however, with proper
and aggressive therapy, many survive. Some authors have suggested that the mortality
rate approaches 50%. The mortality rates reported in animals with generalized
peritonitis treated with open abdominal drainage have varied from 20% to 48%.
References
Swann H, Hughes D: Diagnosis and management of peritonitis, Emergency Surgical
Practice, Vet Clin North Am Small Anim Pract 30:603, 2000.
Hardie EM: Life-threatening bacterial infection, Compend Cont Educ Pract Vet 17:763,
1995.
Harvey HJ: Complications of small intestinal biopsy in hypoalbuminemic patients, Vet
Surg 19:289, 1990.
Pablo LS, Bailey JE: Etomidate and telazol, Vet Clin North Am Small Anim Pract
29:779, 1999.
Suggested reading
Hauptman JG, Walshaw R, Olivier NB: Evaluation of the sensitivity and specificity of
diagnostic criteria for sepsis in dogs, Vet Surg 26:393, 1997.
King LG: Postoperative complications and prognostic indicators in dogs and cats with
septic peritonitis: 23 cases (1989-1992), J Am Vet Med Assoc 204:407, 1994.
Selected abstracts of recent manuscripts
Guler O, Ugras S, Aydin M, Dilek FH, Dilek ON, Karaayvaz M. The effect of
lymphatic blockage on the amount of endotoxin in portal circulation, nitric oxide
synthesis, and the liver in dogs with peritonitis. Jpn J Surg 29:735 1999. This
study was performed to investigate the effect of lymphatic blockage on the amount of
endotoxin in portal venous blood, nitric oxide synthesis, the release of aspartate
aminotransferase from the liver, hepatic damage, and survival in an experimental model
of peritonitis in dogs. The animals were divided into control, unligated thoracic duct
peritonitis, and ligated thoracic duct peritonitis groups. The results of this study showed
that the blockage of lymph flow has a negative effect on the liver and survival in dogs
with peritonitis.
Jang SS, Breher JE, Dabaco LA, Hirsch DC. Organisms isolated from dogs and
cats with anaerobic infections and susceptibility to selected antimicrobial agents.
J Am Vet Med Assoc 210:1610, 1997. Specimens from 1267 dogs and 243 cats were
studied using standard anaerobic and aerobic bacterial culture methods. Obligate
anaerobic bacteria were isolated from 15.7% of the specimens from dogs and 28.4% of
the specimens from cats. All of the obligate anaerobic specimens tested were
susceptible to amoxicillin-clavulanic acid and chloramphenicol, and most were
susceptible to metronidazole. Only 71% of the Bacteroides isolates were susceptible to
ampicillin, and only 83% were susceptible to clindamycin. Only 80% of the Clostridium
isolates were susceptible to clindamycin, but all were susceptible to ampicillin.
Ludwig LL, McLoughlin MA, Graves TK, Crisp MS. Surgical treatment of bile
peritonitis in 24 dogs and 2 cats: a retrospective study (1987 - 1994). Vet Surg
26:90, 1997. The medical records of dogs and cats surgically treated for biliary
effusions at two university hospitals were reviewed. The most common causes were
trauma and necrotizing cholecystitis. Determination of the bilirubin concentration of the
abdominal effusion was the only diagnostic test that was 100% effective in diagnosing
bile leakage before surgical intervention. The bilirubin concentration of the effusion was
consistently at least two times higher than the serum bilirubin concentrations. Patients
with sterile biliary effusions were found to have a much lower mortality rate than those
with septic biliary effusions.
Nagy KK, Perez F, Fildes JJ, Barrett J. Optimal prosthetic for acute replacement
of the abdominal wall. J Trauma Injur Infect Crit Care 47:529, 1999. SpragueDawley rats were used to compare two prostheses for repair of acute abdominal wall
defects in the presence and absence of peritonitis. Gore-Tex dual-mesh expanded
polytetrafluorethylene (PTFE) and Dexon polyglycolic acid mesh (PGA) were used to
cover experimentally created full thickness wall defects. Abdominal contamination was
created by injecting a stool slurry intraperitoneally in some rats. At the end of 3 weeks,
the rats were killed. The density of abdominal adhesions was graded, and the extent of
reepithelialization was noted. PTFE was found to be superior to PGA as a replacement
prosthesis for acute abdominal wall defects. PTFE was found to be associated with
fewer adhesions, improved epithelialization of the wound, and less morbidity and
mortality. This finding was especially true with intraperitoneal fecal soilage.
Runk A, Allen SW, Mahaffey EA. Tissue reactivity to poliglecaprone 25 in the
feline linea alba. Vet Surg 28:466, 1999. Poliglecaprone 25 was evaluated for tissue
reactivity when used for all ligations and abdominal wall closure in routine feline
ovariohysterectomies. The inflammatory reactions seen were consistent with those
anticipated after implantation of suture material in a surgically created wound. There
were no dehiscences in the study animals. The findings supported the clinical use of
this suture material for fascial closure in cats.
Shaher R, Shamir MH, Niebauer GW, Johnston DE. A possible association
between acquired nontraumatic inguinal and perineal hernia in adult male dogs.
Can Vet J 37:614, 1996. Previously reported cases of male dogs over the age of 4
years with nontraumatic inguinal hernias were reviewed. Nine cases were identified
between 1941 and 1994, four of which also had perineal hernias. The medical records
of five male dogs with nontraumatic inguinal hernias presenting to the Veterinary
Teaching Hospital-Koret School of Veterinary Medicine between 1989 and 1995 were
also reviewed. All five of these dogs had concurrent perineal hernias. The authors
hypothesize that there is a common pathogenesis in the development of inguinal and
perineal hernias in adult male dogs and suggest that every adult male dog with an
inguinal hernia be carefully examined for a coexisting perineal hernia.