Canis ISSN: 2398-2942

Hiatal hernia

Contributor(s): James Simpson, Kenneth Simpson, Rachel Burrow

Introduction

  • Protrusion of an abdominal viscus into thoracic cavity through esophageal hiatus.
  • Low incidence.
  • Can occur as congenital or acquired condition.
  • Classified according to position of gastro-esophageal sphincter: axial, para-esophageal, combined.
  • Cause: associated with stretching or laxity of the phrenico-esophageal ligament which allows herniation of the abdominal esophagus, gastroesophageal junction, gastric cardia, fundus and other abdominal organs.
  • Signs: may be constant or intermittent and include salivation, dysphagia, vomiting, regurgitation, hematemesis, dyspnea, aspiration pneumonia, orthopnea, exercise intolerance, weight loss, cachexia, and jaundice.
  • Diagnosis: history, clinical signs, radiography, esophagoscopy.
  • Treatment: medical management is attempted initially, correction of concurrent upper airway obstruction if present, surgical treatment in cases non-responsive to medical management (especially for congenital cases).
  • Prognosis: good following surgery.

Pathogenesis

Etiology

  • This condition is likely to have a complex, multifactorial etiology and pathophysiology involving a number of interrelated factors including displacement of the gastro-esophageal sphincter, changes in the angle of insertion of the esophagus into the stomach, anatomical changes to the hiatal canal and phrenico-esophageal ligament, esophageal motility disorders, underlying respiratory, neurological or neuromuscular disease. Upper respiratory obstruction may exacerbate the clinical signs associated with hiatal hernia. Hiatal hernia has also been reported following surgical correction of chronic diaphragmatic hernia Diaphragm: repair of diaphragmatic defects.
  • Congenital cases have been proposed to result from congenital weakening or incomplete development of phrenico-esophageal ligament.
  • Trauma (in acquired cases).

Specific

  • Prior trauma.

Pathophysiology

  • Phrenico-esophageal ligament around esophageal hiatus is congenitally weakened or incomplete, allowing abdominal organs to move into thoracic cavity.
  • Abdominal esophagus and stomach are most frequently herniated.
  • Classified according to position of gastro-esophageal sphincter (GOS):
    • Axial: GOS found cranial to esophageal hiatus, many are "sliding", ie the abdominal esophagus +/- part of stomach herniate intermittently. This is the commonest type of hiatal hernia.
    • Para-esophageal: GOS occupies a normal position while fundus/other abdominal viscus herniates through phrenico-esophageal ligament.
    • Combined: both GOS and other abdominal organs lie cranial to the hiatus.
  • When GOS moves through the hiatus into thorax, thoracic pressure (being lower than intra-abdominal pressure) allows gastro-esophageal reflux → esophagitis Esophagitis.
  • Esophagitis further decreases the gastro-esophageal pressure resulting in further tendency for gastro-esophageal reflux.
  • Esophageal irritation or GOS obstruction results in hypersalivation, vomiting or regurgitation.
  • Abnormal/reduced esophageal motility and mega-esophagus may be present in some cases. This may be primary or secondary to the hiatal hernia.
  • Weight loss or cachexia follows in severe cases.
  • Aspiration pneumonia follows persistent vomiting/regurgitation.
  • Herniation of duodenum can occur with resulting obstruction of the common bile duct and jaundice has been recorded but is rare.
  • Increased inspiratory effort may cause an increase in negative intra-esophageal and intrapleural pressure so that the abdominal esophagus and part of the stomach are "pulled" into the thorax by the increased pressure differential between intra-abdominal and intrapleural pressure.
  • The presence of acid in the lower esophagus can cause laryngo- and bronchospasm which further worsen the respiratory signs.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Sivacolundhu R K et al (2002) Hiatal hernia controversy - a review of pathophysiology and treatment options. Aust Vet J 80 (1-2), 48-53 PubMed.
  • Lorinson D & Bright R M (1998) Long-term outcome of medical and surgical treatment of hiatal hernias in dogs and cats: 27 cases (1978-1996). JAVMA 213 (3), 381-384 PubMed.
  • Pratschke K M et al (1998) Hiatal hernia as a complication of chronic diaphragmatic herniation. JSAP 39 (1), 33-38 PubMed.
  • Callan M B et al (1993) Congenital esophageal hiatus hernia in the Chinese Shar-pei dog. J Vet Intern Med 7 (4), 210-215 PubMed.
  • Bright R M, Sackman J E, DeNovo C & Toal C (1990) Hiatal hernia in the dog and cat - a retrospective study of 16 cases. JSAP 31 (5), 244-250 VetMedResource.
  • Williams J M (1990) Hiatus hernia in a Shar-pei. JSAP 31 (5), 251-254 WileyOnlineLibrary.
  • Burnie A G et al (1989) Gastro-esophageal reflex and hiatus hernia associated wtih laryngeal paralysis in a dog. JSAP 30 (7), 414-416 WileyOnlineLibrary.
  • Prymak C et al (1989) Hiatal hernia repair by restoration and stabilzation of normal anatomy. An evaluation in four dogs and one cat. Vet Surg 18 (5), 386-391 PubMed.


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