Definition

Passive, retrograde movement of undigested gastric or esophageal contents into the oral cavity. Reflux refers to the retrograde movement of gastric juice across the gastroesophageal sphincter into the esophagus.

Pathophysiology

Regurgitation results from a loss of normal esophageal motility. In the normal esophagus, the presence of a food bolus in the proximal esophagus stimulates afferent sensory neurons. Signals are transferred centrally, via the vagus and glossopharyngeal nerves, to the tractus solitarius and nucleus ambiguus. Motor impulses travel back via the vagus nerve to stimulate striated muscle (canine) and striated and smooth muscle (feline) to cause esophageal peristalsis. Lesions anywhere along this pathway may lead to regurgitation.

Systems Affected

• Gastrointestinal-dysphagia, weight loss
• Musculoskeletal-weakness, weight loss
• Nervous-polyneuropathies, CNS disease
• Respiratory-aspiration pneumonia

Genetics

• Regurgitation due to megaesophagus can be inherited in wirehaired fox terriers (autosomal recessive) and miniature schnauzers (autosomal dominant or 60% penetrance autosomal recessive). A breed predisposition also exists for the German shepherd, great Dane and Irish setter. The site and pathogenesis of the lesion in idiopathic megaesophagus is unknown. Suggested hypotheses include abnormalities of the afferent limb of the reflex arc (receptors, neurons) or of the swallowing center in the CNS.
• Boxers and Newfoundlands have a genetic predisposition for inflammatory myopathy that is associated with esophageal dysmotility.
• Brachycephalic breeds are predisposed to sliding hiatal hernias (type I) that is typically associated with gastroesophageal reflux.

Incidence/Prevalence

N/A

Geographic Distribution

N/A

Signalment

Signs

Causes

Risk Factors

Increased risk of gastroesophageal reflux with general anesthesia; the resultant esophagitis may lead to stricture formation and regurgitation.

Differential Diagnosis

• Regurgitation is a clinical sign, not a diagnosis, and is the hallmark of esophageal disease.
• It is important to differentiate vomiting from regurgitation.

CBC/Biochemistry/Urinalysis

• There are no pathognomonic changes for regurgitation.
• Inflammatory leukogram may be seen if aspiration pneumonia is present.
• Most helpful for evaluation of possible underlying etiologies: e.g., erythrocyte changes with lead toxicosis, elevated CK with myopathy, hyperkalemia and hyponatremia with hypoadrenocorticism, hypercholesterolemia with hypothyroidism.

Other Laboratory Tests

These elucidate etiologies of acquired conditions causing regurgitation and include ACTH stimulation test or baseline cortisol level (hypoadrenocorticism); thyroid serology (hypothyroidism); acetylcholine receptor antibody level (myasthenia gravis); blood lead levels (toxicosis).

Imaging

• Thoracic and cervical radiography-evidence of a gas-, fluid-, or ingesta-filled esophagus with megaesophagus; may also show aspiration pneumonia, neoplasia, foreign bodies, hiatal hernia, etc.
• Contrast studies-both liquid barium and barium-coated food for radiolucent foreign bodies or esophageal strictures. Iohexol may also be used. Esophagram does not allow one to evaluate functional disorders such as intestinal dysmotility or cricopharyngeal achalasia. Caution: contrast studies may increase the risk for aspiration pneumonia with regurgitation.
• Videofluoroscopy-for pharyngeal weakness, cricopharyngeal dysphagia, esophageal motility disorders, hiatal hernia or gastroesophageal reflux.
• Other imaging studies include scintigraphy and high-resolution manometry for motility evaluation and ultrasound for pharyngeal or cervical masses.
• Cervical and thoracic CT scans may also be utilized.

Diagnostic Procedures

• Esophagoscopy can be useful for esophagitis, strictures, vascular ring anomalies, neoplasia, and foreign bodies.
• Electromyography and nerve/muscle biopsies may be used for neuropathic or myopathic conditions.
• Transtracheal wash or bronchoalveolar lavage if aspiration pneumonia is present or suspected.

Pathologic Findings

Gross and histologic findings depend upon the underlying etiology and the presence of complicating factors.

Appropriate Health Care

• Therapy for underlying etiology should be instituted.
• Important to meet nutritional requirements and treat or prevent aspiration pneumonia.

Nursing Care

• Aspiration pneumonia may require supplemental oxygen therapy, nebulization/coupage, and fluid therapy with balanced electrolyte solution.
• These animals may be recumbent and require soft bedding. They should be maintained in sternal recumbency or turned to alternate down sides every 4 hours.

Activity

Depending on etiology, restricted activity is not necessary.

Diet

• Experimentation with different food consistencies is essential. Liquid gruel, small meatballs, or blenderized slurries may be used.
• Some cases benefit from gastrostomy feedings, though regurgitation may still occur.
• Both food and water should be elevated, and animal should be maintained in an upright position for 10–15 minutes after eating or drinking. Use of a Bailey chair facilitates keeping the dog upright for 10–15 minutes after a meal.
• The recommend caloric requirement amount should be calculated and the diet should be monitored so that basic energy requirements are met.

Client Education

• If regurgitation is due to megaesophagus, most cases require life-long therapy, even if an underlying etiology is found. Client dedication is important for long-term management.
• Most animals succumb to aspiration pneumonia or intractable regurgitation.
• Placement of a PEG tube in dogs with megaesophagus can reduce the frequency of aspiration pneumonia.

Surgical Considerations

• Surgical intervention is indicated for vascular ring anomalies, cricopharyngeal achalasia, bronchoesophageal fistula, and others.
• Esophageal dysfunction is permanent in most cases.
• Balloon dilation is indicated for cases of esophageal stricture.

Drug(s) Of Choice

• Antibiotics for aspiration pneumonia (broad-spectrum or based on culture and sensitivity from TTW or BAL).
• Specific therapy for underlying etiology if indicated.
• Prokinetics-metoclopramide (0.2–0.4 mg/kg SC or PO q6–12h, or 1–2 mg/kg q24h as a CRI) increases lower esophageal sphincter tone and increases gastric motility. Cisapride (0.5 mg/kg PO q8–12h) is more effective for esophageal reflux than metoclopramide and has been documented to enhance gastric emptying and increase lower esophageal sphincter tone in dogs.
• Other motility agents (e.g., nizatidine) have not been evaluated for esophageal motility.
• H₂ blockers for esophagitis-ranitidine (1–2 mg/kg PO, IV q12h), famotidine (0.5–1 mg/kg PO, SC, IM, IV q12h). Proton pump inhibitors may be used in severe cases-omeprazole (0.7–1.5 mg/kg PO q24h).

Contraindications

N/A

Precautions

• Absorption of orally administered drugs may be compromised.
• Injectable forms should be used when applicable.

Possible Interactions

N/A

Alternative Drug(s)

N/A

Patient Monitoring

• Animals with aspiration pneumonia should have thoracic radiographs and complete blood counts checked until resolution, or if recurrence is suspected.
• Animals should be monitored, weighed, and body condition scores applied to ensure adequate caloric intake.

Prevention/Avoidance

N/A

Possible Complications

• Aspiration pneumonia.
• Others depending on presence of underlying diseases (e.g., hypothyroidism).

Expected Course and Prognosis

• Older animals with idiopathic megaesophagus have a poor prognosis.
• Aspiration pneumonia is the typical cause of death or euthanasia.

Associated Conditions

• Aspiration pneumonia
• Megaesophagus

Age-Related Factors

Young animals may regain some esophageal function with appropriate therapy, depending on etiology.

Zoonotic Potential

None

Pregnancy/Fertility/Breeding

N/A

See Also

• Dysautonomia (Key-Gaskell Syndrome)
• Dysphagia
• Esophagitis
• Megaesophagus
• Myasthenia Gravis
• Pneumonia, Bacterial

Abbreviations

• ACTH = adrenocorticotropic hormone
• BAL = bronchoalveolar lavage
• CK = creatine kinase
• CT = computed tomography
• PEG = percutaneous gastrostomy tube
• TTW = transtracheal wash

Client Education Handout Available Online