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384 Gastrointestinal Obstruction

Gastrointestinal Obstruction Bonus Material Client Education
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BASIC INFORMATION
• Dehydration, depression, or shock; with
proximal and complete obstructions ○ Hypokalemia: 25%
○ Hyponatremia: 20% (occurs more com-
Definition monly with linear than discrete foreign
Common disorder caused by a foreign object Etiology and Pathophysiology bodies)
or mass that partially or completely occludes Causes of GI tract obstruction: • Metabolic alkalosis with proximal obstruc-
the pylorus or intestinal lumen. Obstructions • Foreign body tion; metabolic acidosis with hypoperfusion,
caused by gastric dilation and volvulus (p. 377), • Mass sepsis secondary to peritonitis, or other
mesenteric volvulus (p. 649), linear foreign • Intussusception systemic effects
bodies (p. 353), and intussusception (p. 561) • Linear foreign body Abdominal radiographs: often the most
are discussed separately. • Trichobezoar informative test. Urgent consultation with a
• Volvulus or torsion radiologist can be helpful:
Synonyms • Stricture or adhesion • Radiopaque foreign objects may be visualized.
Intraluminal obstruction, intestinal blockage Mechanism: • Fluid- or gas-distended intestinal loops
• Physical obstruction of the intestinal lumen • Pathologic dilation of intestinal loops:
Epidemiology causes mechanical ileus, and fluid and gas small-bowel lumen should not exceed the
SPECIES, AGE, SEX accumulation proximal to the obstruction. diameter of twice the width of a rib or be
Gastrointestinal (GI) obstruction can occur in • Duodenal and proximal jejunal obstruction is greater than 1.6 times the height of the fifth
dogs or cats of either sex. Foreign body obstruc- often associated with acute and severe signs. lumbar vertebra.
tion is more common in dogs, likely related to • Persistent vomiting and loss of gastric secre- • Radiographs that demonstrate a foreign body
their behaviors (e.g., chewing rawhides, bones, tions associated with proximal obstructions must be recent (minutes or hours before
toys). Younger animals are more likely to ingest may lead to electrolyte imbalances (hypo- induction of general anesthesia or, better
foreign material, and older animals are more chloremic metabolic alkalosis). still, retaken just after induction) if surgery
likely to have a neoplastic obstruction. • Lymphatic and capillary stasis causes intes- is planned. A gastric or duodenal foreign
tinal wall edema. body can be displaced into the esophagus
RISK FACTORS • Impaired intestinal mucosal barrier allows during anesthetic induction, and an intestinal
• Younger animals are at greater risk for bacterial translocation, potentially result- foreign body might have been defecated since
dietary indiscretion and therefore foreign ing in endotoxemia, sepsis, or rarely, septic the original radiographs were taken.
body ingestion. peritonitis without intestinal necrosis or Thoracic radiographs: older animals with
• Some animals are more prone to ingesting perforation. suspected neoplasia to look for metastasis
foreign objects than others (individual • High intraluminal pressure causes intestinal
behavior), irrespective of age. wall ischemia that may progress to necrosis Advanced or Confirmatory Testing
• Older animals are at greater risk for neoplasia. and peritonitis. Contrast radiographs:
• Barium sulfate suspension for upper GI study
ASSOCIATED DISORDERS DIAGNOSIS unless perforation suspected (p. 1172)
Animals with diseases that cause pica are more ○ If perforation suspected, consider using
at risk for foreign object ingestion. Diagnostic Overview nonionic iodinated contrast medium or
The diagnosis is suspected based on history other diagnostic techniques (abdomino-
Clinical Presentation and physical exam, is supported by imaging centesis, peritoneal lavage).
HISTORY, CHIEF COMPLAINT (radiographic and/or ultrasonographic) findings, • Barium enema
• Vomiting, anorexia, and depression are and is confirmed by endoscopy or surgery. ○ For assessing an obstructive pattern in the
common primary complaints. Diagnostic imaging should be considered in distal intestine
• Severity of clinical signs varies, depending any young animal that presents with vomiting, ○ For differentiating small bowel from large
on duration and location of obstruction. anorexia, or a painful abdomen or has a history bowel if it is not clear whether a gas-
• Proximal and complete obstructions are of foreign body ingestion. filled viscus is a pathologically distended
associated with more severe clinical signs segment of small intestine or the normal
of illness. Differential Diagnosis colon
• History of being unable to hold down water • Vomiting (pp. 1293 and 1294) Abdominocentesis (p. 1056) and fluid analysis
is very suspicious for GI obstruction. • Functional ileus (p. 1343)
• Distal or partial obstructions may be associ- ○ Infectious disease of the GI tract (parvo- • If perforation/peritonitis suspected
ated with vague and chronic signs such as viral or coronaviral enteritis) Abdominal ultrasound:
intermittent vomiting, anorexia, weight ○ Intoxication • Site of obstruction may be visualized.
loss, or diarrhea. When associated with GI ○ Dysautonomia • Identification of small amounts of free
obstruction, diarrhea is usually scant and abdominal fluid
not profuse. Initial Database • Localization of free fluid for accurate centesis
• Intermittent obstruction of the pylorus by CBC, serum biochemistry profile, and • Ultrasonographic evidence of the intestinal
gastric foreign bodies results in intermittent urinalysis: diameter enlargement of the jejunum >
clinical signs. • Evidence of dehydration (e.g., blood urea 1.5 cm suggests an obstruction. Ultraso-
nitrogen, creatinine elevations with urine nography was definitive for obstruction in
PHYSICAL EXAM FINDINGS specific gravity > 1.030; hemoconcentration/ 97% of dogs (compared with 70% accuracy
• Abdominal splinting or signs of pain on elevated packed cell volume) on radiographs) in a recent study.
palpation may be noted. • Electrolyte imbalances Diagnostic peritoneal lavage:
• Mass or foreign object may be identified ○ Hypochloremia occurs in 51% of cases • If peritonitis is suspected but centesis is
with careful palpation. and is the most common abnormality. unrewarding

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