Definition

An abrupt fixed narrowing of the esophagus due to scar tissue, resulting in partial or complete obstruction.

Pathophysiology

• Benign strictures occur when there is severe esophagitis, occurring for greater than 270° of the esophageal circumference. Regardless of the initiating event, once esophagitis develops, there is a decrease in LES tone. This results in more acid reflux and subsequent worsening of the esophagitis. Once severe esophagitis is present, damage can extend to the lamina propria and muscularis layers. This incites a fibroblastic proliferation and contraction, leading to stricture formation.
• Malignant strictures occur rarely in dogs and cats, and stricture results from direct tumor invasion.

Systems Affected

• Gastrointestinal-the esophagus is usually affected focally, although multiple strictures can occur.
• Respiratory-regurgitation is common with strictures, with secondary aspiration pneumonia.

Genetic

None.

Incidence/Prevalence

Uncommon

Geographic Distribution

Spirocerca lupi granuloma occurs in the southern USA, parts of Europe, South Africa, and Israel. There is no other geographic distribution.

Signalment

Dog and cat. No known breed or sex predilections. Puppies and kittens with vascular ring anomaly become symptomatic at weaning.

Signs

• Pain during swallowing (odynophagia), dysphagia, increased salivation, regurgitation, anorexia, and weight loss. Signs tend to be progressive as the stricture progressively narrows.
• If regurgitation leads to aspiration pneumonia, cough and dyspnea can develop.

Causes

• Reflux during anesthesia is the most common cause of benign esophageal stricture, accounting for about ∼ 65% of cases. It is presumed that decreased LES tone occurring during anesthesia allows for gastroesophageal reflux, which results in subsequent acid injury to the esophageal mucosa.
• Severe esophageal foreign bodies (if >270° mucosal damage occurs).
• Tablets and capsules can induce esophagitis leading to stricture. The most commonly incriminated drugs are doxycycline, clindamycin and aspirin.
• Gastroesophageal reflux independent of anesthesia.
• Prolonged vomiting of gastric contents.
• Swallowing of caustic substances.
• Esophageal neoplasia (squamous cell carcinoma and lymphoma most common).
• Vascular ring anomaly (congenital).
• Spirocerca lupi granuloma.

Risk Factors

• General anesthesia, especially with drugs that decrease LES tone or when the table is tilted head-down,
• Oral medications given with a dry swallow (60–80% of capsules do not pass into the stomach after 5 minutes following a “dry” swallow)
• Foreign body ingestion.

Differential Diagnosis

• Megaesophagus
• Esophageal foreign body
• Esophageal neoplasia
• Extrinsic esophageal compression (mass, abscess)
• Gastroesophageal reflux
• Vomiting (any cause)
• Oropharyngeal dysphagia

CBC/Biochemistry/Urinalysis

Usually unremarkable. May have neutrophilic leukocytosis if secondary aspiration pneumonia develops.

Other Laboratory Tests

Usually unremarkable

Imaging

• Thoracic radiographs-usually unremarkable, unless secondary aspiration pneumonia develops. Occasionally gas-filled dilation cranial to the stricture may be seen.
• Videofluoroscopic barium swallow-procedure of choice. If videofluoroscopy is not available, barium swallow of liquid, paste, or food followed immediately by radiography is performed. Peristalsis proximal to the stricture site can be abnormal with concurrent esophagitis. Usually recognize an abrupt narrowing of the esophageal lumen at the stricture site. Most easily demonstrated with canned food or kibble mixed with barium. May demonstrate more than one stricture. Most cases of reflux-induced strictures are between the heart base and diaphragm. Most cases of pill-induced strictures are near the thoracic inlet (especially cats).

Diagnostic Procedures

Endoscopy-There is an abrupt decrease in luminal diameter at the stricture site. Usually the mucosa is normal (smooth and pink), but can appear hyperemic and ulcerated if esophagitis is present. Often the scope cannot be advanced beyond the stricture without balloon dilation. The location of the stricture should be measured from the upper canine teeth.

Pathologic Findings

If an esophageal mass is present, biopsy with histopathology is warranted. Otherwise, benign strictures do not need to be biopsied. Variable degree of esophagitis may be seen.

Appropriate Health Care

Outpatient medical management is only successful for mild strictures. More severe strictures will lead to progressive malnutrition and possible aspiration pneumonia, and require inpatient intervention. If there are complications (esophageal perforation, aspiration pneumonia), then inpatient care is required.

Nursing Care

With mild strictures, gruel feeding (ideally partially elevated) may be possible. With more severe strictures, oral alimentation is not possible. Intravenous fluids may be necessary if animal is dehydrated. Other medications depend on the presence of esophagitis, complications, and results of dilation.

Activity

Mild exercise restriction may be necessary after dilation. If pneumonia is present, the degree of hypoxia will determine appropriate activity level.

Diet

With mild strictures, gruel feeding (ideally partially elevated) may be possible. Recommend feeding a fat-restricted diet to enhance gastric emptying. Canned food can be fed in small frequent amounts following dilation, even when severe esophageal tearing occurs. In some cases, re-stricturing occurs necessitating percutaneous endoscopic gastrostomy (PEG) tube feeding while multiple dilations are employed.

Client Education

• With mild strictures, gruel feeding (ideally partially elevated) may be possible. Otherwise dilation procedures are necessary.
• Owners should be aware that dilation procedures are not always successful, and that multiple attempts are required in some patients. It is important that medical management for esophagitis be diligently employed following dilation procedures to reduce the risk of re-stricture.
• Most cases have a successful outcome.
• If there is failure after ∼5–8 attempts, rescue procedures (such as stent placement) should be considered.
• Patients with esophageal neoplasia have a poor prognosis.

Surgical Considerations

• The first-line treatment of benign esophageal strictures is mechanical dilatation of the stricture. Techniques have evolved from rigid bougienage, to flexible bougies, to balloon dilation. The latter technique is generally thought to be superior to bougienage, but objective evidence for this is lacking in human and veterinary patients. The theoretical advantage of balloon dilatation is that the forces applied to the stricture are a radial stretch, whereas some of the forces applied with bougienage are also longitudinal, resulting in greater potential for esophageal perforation.
• Esophageal dilatation balloons are made of special plastic that makes the balloon extremely rigid when maximally inflated at high pressures, generally up to 45 psi. Balloons are positioned within the stricture under direct endoscopic visualization. The balloon is slowly inflated until it reaches the manufacturer's rated pressure for that balloon. Sequentially larger balloons are used until the clinician subjectively judges the degree of mucosal tearing to be acceptable.
• The technique is very subjective in veterinary medicine, with many variables not defined by controlled studies. These include the sequence of dilatation, the optimal final dilation diameter, use of corticosteroids intralesionally, post-dilation drugs, post-dilation feeding regime, the elective use of percutaneous endoscopic gastrostomy (PEG) tubes, and repeat elective dilatations (and at what interval). Typically, an initial balloon diameter is selected that is 50–100% larger than the estimated stricture diameter. If there is doubt, selection of a smaller balloon with gradually larger subsequent dilations is safest. The sequence of subsequent larger dilations is then determined by the degree of mucosal tearing. The final dilation diameter is usually chosen by the degree of mucosal tearing and the size of the patient. As a general guideline, the end diameter is as follows: cats and dogs <8 kg, 12 mm; dogs 8–15 kg, 16 mm; dogs 15–30 kg, 20 mm; dogs 30–50 kg, 25 mm; and dogs >50 kg, 30 mm. This is subjective, and is a balance between the desire to achieve a large enough lumen at the completion of procedure and the risk of perforation when too large a balloon is used.
• Injection of intralesional submucosal triamcinolone in a 4-quadrant pattern just prior to dilation may reduce the frequency of re-stricture. Similarly, topical application of mitomycin-C may also reduce the frequency of re-stricture. Both methods can be employed in the same patient.
• Some authors recommend elective dilations at 1-week intervals to decrease the likelihood of re-stricture formation. I do not routinely recommend this since the published median number of dilations required for successful treatment is 2 (range 1–5). If 3 dilations are required, then I often recommend an elective dilation 1 week later.
• If >5–8 dilations have been performed with subsequent stricture recurrence, a salvage procedure with placement of a self-expanding covered metal stent can be employed. It is important that the stent be secured with sutures to prevent stent migration.
• Surgical management (resection and anastomosis) is only performed as a last resort.

Drug(s) Of Choice

• Following dilation, give sucralfate suspension (0.5–1 gram/patient PO q6h) to reduce esophagitis and pain. Medications for esophagitis are used, including cisapride (0.5–0.75 mg/kg PO q8h) to increase LES tone and enhance gastric emptying, and omeprazole (1 mg/kg PO q12h) to decrease gastric acid.
• Broad-spectrum antibiotics are used if aspiration pneumonia is present.

Contraindications

Caustic substances and emetic medications

Precautions

Esophageal perforation can occur with overzealous balloon dilation of the stricture. Therefore sequentially increase diameter of balloons.

Possible Interactions

Sucralfate may inhibit the absorption of other drugs.

Alternative Drug(s)

Metoclopramide can be used to increase LES tone (although cisapride is superior). Histamine H₂-receptor blockers can be used to decrease gastric acid (although proton pump inhibitors are superior).

Patient Monitoring

• Clinical signs are monitored for stricture recurrence (mainly regurgitation). An appropriate consistency food should be fed. Repeat stricture dilation should be considered based on recurrence of clinical signs.
• Aspiration pneumonia is monitored by clinical signs and radiographic resolution.

Prevention/Avoidance

• Preanesthetic administration of cisapride decreases the number of reflux events in anesthetized dogs, but the low incidence of stricture may make this an overly aggressive part of routine preanesthetic management.
• Preanesthetic administration of omeprazole will minimize the likelihood of acid reflux and potentially decrease the likelihood of stricture formation.
• Medications with ulcerogenic potential (such as doxycycline, clindamycin, and aspirin) should be given with at least 6 mL of water or food (a “wet swallow”).

Possible Complications

• Complications of balloon dilatation include perforation, severe mucosal tearing and esophagitis, and re-stricture.
• Aspiration pneumonia secondary to regurgitation.
• Complications of stent placement include stent migration, tissue ingrowth into the stent resulting in stent occlusion, food obstruction, hemorrhage, perforation, airway compression, pressure necrosis/fistula formation, dysphagia, and pain.

Expected Course and Prognosis

• The overall successful treatment rate of balloon dilatation is reported to be between 70% and 88% in dogs and cats. The median number of dilations required for successful treatment is 2, but can require up to 5–8 before considered a failure. Prognosis is poorer with narrower and more chronic strictures.The prognosis for esophageal neoplasia is poor.

Associated Conditions

Aspiration pneumonia, esophagitis.

Age-Related Factors

None.

Zoonotic Potential

None.

Synonyms

• Esophageal narrowing
• Esophageal blockage or obstruction

See Also

• Regurgitation
• Megaesophagus
• Dysphagia
• Esophageal foreign body
• Esophagitis
• Gastroesophageal reflux

Abbreviation

LES = lower esophageal sphincter

Client Education Handout Available Online