Diaphragmatic hernia

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Diaphragmatic hernia in a dog, showing radiographic evidence of loss of integrity of the diaphragm, and presence of abdominal contents in the thoracic cavity[1]

Diaphragmatic hernia is usually a trauma-associated condition but occasionally occurs as a congenital condition[2].

Congenital diaphragmatic hernias occur as a consequence of failure of the pleuroperitoneal folds to fuse with other parts of the developing diaphragm (particularly the septum transversum) or as a result of an incomplete closure of the pleuroperitoneal canals on the ventral part of the diaphragm[3]. In human medicine, congenital diaphragmatic hernias have been linked to vitamin A deficiency, and intra-uterine exposure to NSAIDs and nitrofen herbicide[4].

In more rarer cases, diaphragmatic hernia in dogs may occur as a result of intrauterine fetal injury[5] or from the congenital disease situs inversus totalis[6].

The most frequent places for congenital hernias are the sterno-costal triangle (the Morgagni’s foramen, the Larrey’s space) and the lumbocostal triangle (the Bochdalek’s foramen)[7][8][9].

In dogs, peritoneopericardial diaphragmatic hernia is the most common type of congenital defect of the diaphragm and pericardium[10].

The pleural cavity may contain the liver, intestines, spleen and stomach, depending on the extent of the diapragmatic hernia.

In most cases the herniated viscera are located within a hernial sac in the pleural space, surrounded by parietal diaphragmatic pleura and sometimes by peritoneum. This type of hernia, due to the presence of the hernial sac, is called a true hernia[11]. In addition to hernias of the ventral diaphragm, a second group of congenital diaphragmatic hernias consists of esophageal hiatal hernias and sliding perivascular hernias (of the opening of the aorta and the jejunal vein on the side of the cauda)[12].

Esophageal hiatal hernias, frequently reported in the Shar Pei[13][14], can result in secondary megaesophagus[15] as well as pleural effusion due to compromised perfusion of the gastric vasculature.

Acquired diaphragmatic hernias usually develop as a consequence of acute trauma, pregnancy[16] or invasion of retroperitoneal lipomas or sarcomas through the hypaxial musculature[17].

Clinically affected dogs usually present with dyspnea, regurgitation, muffled heart sounds and borborygmi on auscultation and in severe cases, acute shock due to vascular compromise. In chronic cases, more nonspecific symptoms may also be evident such as anorexia, lethargy and weight loss.

Abdominal palpation of the dog may reveal an 'empty' feel to the abdomen, although this depends on the severity of herniation. With traumatic herniation, there may be also be a history of recent trauma, particularly motor vehicle accident.

Diagnosis is usually based on radiographic or CT imaging, which may show the diaphragmatic defect, the presence of visceral organs within the chest cavity, pulmonary edema, cardiomegaly[18] or cardiac tamponade[19]. At least two radiographs, at different angles, are usually required for a valid diagnosis since some radiographic signs are not visible in a single view. The location of the stomach axis and the displacement of tracheal and bronchial segments may assist in establishing a diagnosis[20].

Barium meal radiographs may show delayed emptying of intestinal loops within the thoracic cavity.

A differential diagnosis would include hiatal hernia, megaesophagus or gastroesophageal intussusception[21].

Treatment usually involves various methods of reconstructive surgery using rectus abdominis muscle or connective tissue pedicle flaps or appositional suture placements[22]. A midline laparotomy approach is usually required although some dogs necessitate a median sternotomy, particularly in large herniations. With chronic herniations, adhesions of the lungs or diaphragm to the herniated organs may be necessary to permit reduction of the hernia. Some difficult cases require resection of portions of the lungs, liver, or intestine.

Postoperative complications are usually transient, particularly pneumothorax[23]. Spontaneous lung lobe torsion has been noted as a complication of hernia repair in some dogs[24].

With hiatal hernias, closure of the diaphragmatic hernia is usually accompanied with esophagopexy and tube gastropexy to minimize recurrence[25].

Early surgical correction in cases of congenital hernias are usually curative. With traumatic diaphragmatic hernias, early surgical intervention is essential to prevent hepatic, gastric of intestinal torsion and is usually associated with good perioperative survival rates[26].

References

  1. Ricco CH & Graham L (2007) Undiagnosed diaphragmatic hernia--the importance of preanesthetic evaluation. Can Vet J 48(6):615-618
  2. Choi J et al (2009) Imaging diagnosis - positive contrast peritoneographic features of true diaphragmatic hernia. Vet Radiol Ultrasound 50(2):185-187
  3. Park RD (1998) The Diaphragm. In: Thrall DE, editor. Textbook of Veterinary Diagnostic Radiology. 3rd ed. Philadelphia: WB Saunders Company. pp:294–307
  4. Kling DE & Schnitzer JJ (2007) Vitamin A deficiency (VAD), teratogenic, and surgical models of congenital diaphragmatic hernia (CDH). Am J Med Genet C Semin Med Genet 145C(2):139-157
  5. Suter PF (1984) A Text Atlas of Thoracic Diseases of the Dog and Cat. 1st ed. Wettswil. Thoracic Radiography; pp:179–203
  6. Witsberger TH et al (2009) Situs inversus totalis in a dog with a chronic diaphragmatic hernia. J Am Anim Hosp Assoc 45(5):245-248
  7. Dillon E et al (2000) Congenital diaphragmatic herniation: Antenatal detection and outcome. Br J Radiol 73:360–365
  8. Minneci PC et al (2004) Foramen of Morgagni hernia: Changes in diagnosis and treatment. Ann Thorac Surg 77:1956–1959
  9. Ubee SS et al (2009) Congenital malformation of the diaphragm and left colon: Strangulated Bochdalek hernia in an adult. Surgical Practice 13:24–25
  10. Lojszczyk-Szczepaniak A et al (2011) Retrosternal (Morgagni) diaphragmatic hernia. Can Vet J 52(8):878-883
  11. Kelmer G et al (2008) Diaphragmatic hernia: Etiology, clinical presentation, and diagnosis. Compend Cont Ed Equine Edition 3:28–35
  12. Kim ES et al (2008) A Morgagni diaphragmatic hernia found after removal of mediastinal tumor. Ann Thorac Cardiovasc Surg 14:175–177
  13. Baig MA et al (2006) Budd-Chiari-like syndrome caused by a congenital hiatal hernia in a shar-pei dog. Vet Rec 159(10):322-323
  14. 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
  15. 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
  16. Merbl Y et al (2010) Resolution of persistent pneumothorax by use of blood pleurodesis in a dog after surgical correction of a diaphragmatic hernia. J Am Vet Med Assoc 237(3):299-303
  17. Klosterman ES et al (2012) Transdiaphragmatic extension of a retroperitoneal lipoma into the intrathoracic extrapleural space via the lumbocostal trigone in a dog. J Am Vet Med Assoc 240(8):978-982
  18. Marin LM et al (2007) Vertebral heart size in retired racing Greyhounds. Vet Radiol Ultrasound 48(4):332-334
  19. Little AA et al (2007) Marked pleural effusion causing right atrial collapse simulating cardiac tamponade in a dog. J Am Anim Hosp Assoc 43(3):157-162
  20. Hyun C (2004) Radiographic diagnosis of diaphragmatic hernia: review of 60 cases in dogs and cats. J Vet Sci 5(2):157-162
  21. McGill SE et al (2009) Nonsurgical treatment of gastroesophageal intussusception in a puppy. J Am Anim Hosp Assoc 45(4):185-190
  22. Vereczkei A et al (2012) A new experimental method for hiatal reinforcement using connective tissue patch transfer. Dis Esophagus 25(5):465-469
  23. Minihan AC et al (2004) Chronic diaphragmatic hernia in 34 dogs and 16 cats. J Am Anim Hosp Assoc 40(1):51-63
  24. Spranklin DB et al (2003) Recurrence of spontaneous lung lobe torsion in a pug. J Am Anim Hosp Assoc 39(5):446-451
  25. 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
  26. Gibson TW et al (2005) Perioperative survival rates after surgery for diaphragmatic hernia in dogs and cats: 92 cases (1990-2002). J Am Vet Med Assoc 227(1):105-109
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