Hiatal hernia

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A pup which presented with inguinal, umbilical and hiatal hernia[1]
Radiograph of pup pictured above with oval soft tissue opacity in the caudodorsal thorax. [2]

Hiatal hernia is a genetic disease of dogs characterized by a hernia of the anterior stomach through the diaphragm.

Although this is usually a birth-related defect, it can occur in dogs secondary to diaphragmatic hernia[3], tetanus[4][5] and Duchenne muscular dystrophy (dystrophin-deficient muscular dystrophy)[6].

A hiatal hernia, which occurs more common in dogs with brachycephalic syndrome[7][8], is defined as any protrusion of abdominal contents through the oesophageal hiatus of the diaphragm into the thoracic cavity in the presence of an intact phrenico-oesophageal ligament[9].

Hiatal herniation was thought to be caused by a primary disturbance of the lower oesophageal sphincter[10], but has since been shown to be caused by an abnormality or laxity in the phrenico-oesophageal ligament[11] that allows excessive movement of the oesophagus, gastro-oesophageal junction, gastric cardia and other abdominal organs.

Approximately 60% of cases of hiatal hernia are congenital[12] occurring secondary to incomplete fusion of the diaphragm during early embryonic development[13].

Other congenital defects may also occur such as soft-palate defects[14], umbilical hernia, inguinal hernia and chiari malformations[2].

Four types have been described in the dog:

  • Type I (sliding, axial or oesophageal) - most common in Shar Pei[13], British Bulldog[15] and Chow Chow - axial displacement of the distal part of the oesophagus, the gastro-oesophageal junction and part of the stomach through the oesophageal hiatus into the thoracic cavity[16]
  • Type II (rolling or paraoesophageal) - distal segment of the oesophagus and lower oesophageal sphincter remain in a fixed position but a portion of the fundic region of the stomach herniates into the mediastinum alongside the thoracic oesophagus[17]
  • Type III - rare - mixture of types I and II[18]
  • Type IV - rare - type III complicated by the stomach or other abdominal viscera being located in the paraoesophageal sac[2].

It is important to differentiate between the types of hiatal hernia because the underlying pathology and pathophysiology are different, necessitating different treatments[19].

Clinically affected dogs are often young, or have a long history of vague gastrointestinal signs including regurgitation, coughing, anorexia, dyspnea and ptyalism[20] as a result of reflux esophagitis[21].

Secondary aspiration pneumonia is not uncommon[22], and in rare cases, rupture or strangulation of the short gastric vessels lead to the formation of a hemorrhagic pleural effusion that causes acute severe dyspnea.

Radiographic and CT imaging usually reveals a soft tissue opacity in the caudodorsal thorax as well as varying degrees of pleural effusion[23]. A barium meal swallow may be required to highlight barium in the distended region anterior to teh diaphragm. Fluoroscopy and esophagoscopy are additional ancillary tests available to assist in procuring a diagnosis[24].

A definitive diagnosis usually requires an exploratory celiotomy to confirm the presence of herniation of the gastric cardia, fundus, and body through the esophageal hiatus and an adjacent, distinct defect in the diaphragm.

A differential diagnosis would include gastritis, diaphragmatic hernia, megaesophagus, gastroesophageal intussusception[25] and myasthenia gravis.

Temporary medical relief of symptoms may be achieved with drugs such as omeprazole or cimetidine, however, recurrence of symptoms is common[26].

In most cases, surgical correction of the hernia is required, usually involving surgical reduction of the hernia followed by plication of the oesophageal hiatus, oesophagopexy and left flank gastropexy.

A transient megaesophagus may occur post-operatively but frequently resolves spontaneously[27].

References

  1. Keeley B et al (2008) Congenital oesophageal hiatal hernia in a pug. Ir Vet J 61(6):389-393
  2. 2.0 2.1 2.2 Baig MA et al (2006) Budd-Chiari-like syndrome caused by a congenital hiatal hernia in a Shar-Pei dog. Vet Rec 159:322–323
  3. Pratschke KM et al (1998) Hiatal herniation as a complication of chronic diaphragmatic herniation. J Small Anim Pract 39(1):33-38
  4. Acke E et al (2004) Tetanus in the dog: review and a case-report of concurrent tetanus with hiatal hernia. Ir Vet J 57(10):593-597
  5. Adamantos S & Boag A (2007) Thirteen cases of tetanus in dogs. Vet Rec 161(9):298-302
  6. Baltzer WI et al (2007) Dystrophin-deficient muscular dystrophy in a Weimaraner. J Am Anim Hosp Assoc 43(4):227-232
  7. Poncet CM et al (2005) Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. J Small Anim Pract 46:273–279
  8. Ellison GW et al (1987) Esophageal hiatal hernia in small animals: literature review and a modified surgical technique. J Amer Anim Hosp Assoc 23:391–399
  9. Pairolero PC (1989) Oesophagus and diaphragmatic hernias. In: Principles of Surgery. 5. Schwartz SI, et al, editor. McGraw-Hill, New York
  10. Sivacolundhu RK et al (2002) Hiatal hernia controversies - a review of pathophysiology and treatment options. Aust Vet J 80(1-2):48-53
  11. Prymak C et al (1989) Hiatal hernia repair by restoration and stabilization of normal anatomy: an evaluation of four dogs and one cat. Veterinary Surgery 18:386–391
  12. Guilford WG & Strombeck DR (1996) Diseases of swallowing; In: Strombeck's Small Animal Gastroenterology. Philadelphia. 3. Guilford WG, Center SA, Strombeck DR, Williams DA, Meyer DJ, editor. pp:211–238
  13. 13.0 13.1 Callan MB et al (1993) Congenital esophageal hiatal hernia in the Chinese Shar-Pei dog. J Vet Int Med 7:210–215
  14. Dvir E et al (2003) Congenital narrowing of the intrapharyngeal opening in a dog with concurrent oesophageal hiatal hernia. J Small Anim Pract 44(8):359-362
  15. Hunt GB et al (2002) Hiatal hernia in a puppy. Aust Vet J 80(11):685-686
  16. Gaskell CJ et al (1974) Sliding hiatus hernia with reflux oesophagitis in two dogs. Journal of Small Animal Practice 15(8):503–509
  17. Miles KG et al (1988) Paraesophageal hiatal hernia and pyloric obstruction in a dog. Journal of the American Veterinary Medical Association 193:1437–1439
  18. Williams JM (1990) Hiatal hernia in a Shar-Pei. Journal of Small Animal Practice 31:251–254
  19. Rahal SC et al (2003) Type-4 Oesophageal hiatal hernia in a Chinese Shar-Pei dog. Veterinary Radiology and Ultrasound 44(6):646–647
  20. Lorinson D & Bright RM (1998) Long-term outcome of medical and surgical treatment of hiatal hernias in dogs and cats: 27 cases (1978-1996). J Am Vet Med Assoc 213:381–383
  21. Han E (2003) Diagnosis and management of reflux esophagitis. Clin Tech Small Anim Pract 18(4):231-238
  22. Callan MB et al (1993) Congenital esophageal hiatal hernia in the Chinese shar-pei dog. J Vet Intern Med 7(4):210-215
  23. Gordon LC et al (2010) Hemorrhagic pleural effusion secondary to an unusual type III hiatal hernia in a 4-year-old great dane. J Am Anim Hosp Assoc 46(5):336-340
  24. Lorinson D & Bright RM (1998) Long-term outcome of medical and surgical treatment of hiatal hernias in dogs and cats: 27 cases (1978-1996). J Am Vet Med Assoc 213(3):381-384
  25. McGill SE et al (2009) Nonsurgical treatment of gastroesophageal intussusception in a puppy. J Am Anim Hosp Assoc 45(4):185-190
  26. Guiot LP et al (2008) Hiatal hernia in the dog: a clinical report of four Chinese shar peis. J Am Anim Hosp Assoc 44(6):335-341
  27. Kirkby KA et al (2005) Paraoesophageal hiatal hernia and megaoesophagus in a three-week-old Alaskan malamute. J Small Anim Pract 46(8):402-405