Definition

The partial or complete physical impedance to the flow of ingesta and/or secretions aborally through the pylorus into the duodenum (gastric outlet obstruction) or through the small intestine. Obstructions in the pharynx, esophagus, large intestine, and rectum, and motility disorders are addressed in separate chapters (refer to “See Also”).

Pathophysiology

Systems Affected

• Behavioral-associated with abdominal discomfort or pain (praying position, change in temperament).
• Cardiovascular-hypovolemic shock; tachycardia.
• Gastrointestinal-anorexia; vomiting; diarrhea; and malaise.
• Respiratory-aspiration pneumonia.

Genetics

Unknown (see “Breed Predilections”)

Incidence/Prevalence

Common

Signalment

Signs

Causes

Risk Factors

• Exposure to and tendency to ingest foreign bodies.
• Intussusception-associated with intestinal parasitism and viral enteritis.

Differential Diagnosis

• Metabolic disease (e.g., renal failure, hepatic disease, diabetic ketoacidosis, hypoadrenocorticism).
• Infectious gastroenteritis (e.g., viral, bacterial, parasitic).
• Pancreatitis.
• Peritonitis.
• Toxicity.
• Gastroduodenal ulcer disease.
• Nonspecific gastroenteritis.
• CNS disease.

CBC/Biochemistry/Urinalysis

• These diagnostic tests are useful to rule out other causes for clinical signs (e.g., renal failure, pancreatitis, liver disease, hypoadrenocorticism, diabetic ketoacidosis) and to evaluate overall health status of the patient.
• Hemogram-may reveal anemia from gastrointestinal blood loss, stress leukocytosis, or a degenerative left-shifted leukocytosis or leukopenia due to severe mucosal injury or intestinal perforation with subsequent septic peritonitis.
• Chemistry profile and blood gas analysis-often reveal hypochloremic metabolic alkalosis with gastric outlet obstruction; hypokalemia and prerenal azotemia are variable findings. Hyperlactemia may be present due to hypoperfusion.

Imaging

Diagnostic Procedures

• Gastrointestinal endoscopy-may be useful for confirming gastric and proximal intestinal obstruction and for obtaining biopsies of masses; particularly useful with some types of foreign bodies as retrieval may be possible. This may be performed in conjunction with exploratory laparotomy.
• Abdominal paracentesis or diagnostic peritoneal lavage and cytologic analysis-more sensitive than physical examination and radiography (i.e., can detect small amounts of abdominal effusion); may reveal non-septic inflammation associated with intestinal vascular compromise (prior to perforation) or septic peritonitis; can indicate the need for exploratory laparotomy.

Pathologic Findings

Histopathology of gastrointestinal masses causing obstruction-can reveal granulomatous inflammation, fungal infection (e.g., pythiosis), and neoplasia.

Appropriate Health Care

• Inpatient-for diagnosis, initial supportive medical care, and relief of the obstruction (usually with surgery).
• Surgery-acute intestinal obstructions are emergencies, and surgery should be performed as soon as possible after immediate supportive medical care; intestines do not tolerate vascular compromise well; intestinal resection and anastomosis frequently required (with associated increased morbidity and potential complications), but enterotomy may be successful if earlier diagnosis is made.
• Delay in diagnosis may result in intestinal necrosis, perforation, septic peritonitis, and increased likelihood of death.

Nursing Care

• Intravenous crystalloid fluids-necessary for rehydration, circulatory support, and to correct acid-base and electrolyte abnormalities; for severe circulatory compromise (shock), administer isotonic crystalloid fluids at 90 mL/kg (dogs) or 45–60 mL/kg (cats) over 1 hour.
• Colloids (voluven or hetastarch)-may also be beneficial; frequent evaluation of hydration and electrolytes (with appropriate treatment adjustments) is necessary; for gastric outlet obstruction causing hypochloremic metabolic alkalosis, fluid of choice is 0.9% saline; otherwise, lactated Ringer's solution or other balanced electrolyte solution is adequate.
• Appropriate potassium supplementation-important.

Activity

Restricted

Diet

• Nothing by mouth until relief of obstruction and resolution of vomiting; then feed bland fat-restricted diet for 1–2 days, with gradual return to normal diet.
• Enteral tube feeding or pararenteral feeding may be required postoperatively.

Client Education

Warn that animals with the tendency to ingest foreign bodies are often repeat offenders; all reasonable efforts to prevent access to foreign bodies should be made.

Surgical Considerations

Drug(s)

• Broad-spectrum parenteral antibiotics-with significant mucosal injury or sepsis; ampicillin (20 mg/kg IV q8h) or ampicillin/clavulanate (50 mg/kg IV q8h) and an aminoglycoside (gentamicin 6.6 mg/kg IV q24h, amikacin 15 mg/kg IV q24h) or a fluoroquinolone (enrofloxacin 5–10 mg/kg IV q24h; for cats, ciprofloxacin 10 mg/kg IV q8h). Aminoglycoside antimicrobials should not be used until patient is well hydrated and adverse effects on kidney must be closely monitored via urinalysis (glycosuria, proteinuria, renal casts, decreased urine SG) and assessment of BUN, creatinine, and serum phosphorus values.
• Antiemetics-metoclopramide (0.2–0.5 mg/kg SC or IV q6–8h or 1–2 mg/kg q24h as a CRI); may be given after the obstruction has been relieved; cisapride is more potent than metoclopramide but is only available in an oral form (0.3–0.5 mg/kg q8–12h); maropitant may be used in dogs >8 weeks and cats >16 weeks at 1 mg/kg SC q24h.
• GI protectants-H₂-receptor antagonists (e.g., famotidine 0.5–1.0 mg/kg, SC, IM, IV q12h) and/or the gastric mucosal protectant sucralfate (250 mg/cat PO q8–12h or 250–1,000 mg/dog PO q8–12h)-may be used in patients with mucosal ulceration. Pantoprazole 0.7–1 mg/kg q12–24h.

Contraindications

Prokinetic agents (e.g., metoclopramide and cisapride) must be avoided until obstruction is resolved.

Precautions

Aminoglycoside antibiotics should be not used with shock, dehydration, or renal compromise because of their potential nephrotoxicity.

Patient Monitoring

• Monitor hydration, packed cell volume/total solids, and electrolyte status closely; adjust fluid therapy accordingly.
• Monitor postoperatively for signs of peritonitis.

Prevention/Avoidance

• Clients should be cautioned that some pets with tendencies to ingest foreign bodies may do so repeatedly.
• Efforts to prevent ingestion of foreign bodies are important.

Possible Complications

• Aspiration pneumonia
• Septic peritonitis (intestinal necrosis and perforation, dehiscence)
• Adynamic ileus and/or gastroparesis

Expected Course and Prognosis

• Uncomplicated cases-prognosis good to excellent.
• Intestinal perforation and septic peritonitis-prognosis guarded initially.
• Obstructive granulomatous gastroenteritis-prognosis guarded to poor, especially with pythiosis.
• Mesenteric torsion or volvulus-prognosis poor to grave (most patients die despite surgery).

Age-Related Factors

See “Signalment”

See Also

• Acute Abdomen
• Constipation and Obstipation
• Dysphagia
• Esophageal Foreign Bodies
• Esophageal Stricture
• Gastric Dilation and Volvulus Syndrome
• Gastric Motility Disorders
• Hiatal Hernia
• Hypertrophic Pyloric Gastropathy, Chronic
• Intussusception
• Megacolon
• Megaesophagus
• Pythiosis
• Rectal Stricture
• Regurgitation
• Septic Peritonitis
• Vomiting, Acute
• Vomiting, Chronic

Abbreviations

• CHG = chronic hypertrophic gastropathy
• CNS = central nervous system
• GDV = gastric dilation and volvulus

Client Education Handout Available Online