Hiatal Hernia

Typical Signalment

Dogs that are predisposed to this disorder include:

• Shar pei
• Chow Chow
• Bulldogs
• French Bulldogs

Description

A hiatal hernia is a diaphragmatic abnormality that allows part of the stomach and the abdominal oesophagus to prolapse into the thoracic cavity. Two types of hiatal hernia have been recognized in the dog and cat:

• Sliding hiatal hernia - Cranial displacement of the distal oesophagus and stomach into mediastinum through the oesophageal hiatus.This is the most common form. It can occur in the dog and cat and may occur as a congenital or acquired lesion. Congenital hernias result from incomplete fusion of the diaphragm during early embryonic development.

• Para-oesophageal hiatal hernia - Cranial displacement of part of the stomach into mediastinum through a defect adjacent to the oesophageal hiatus.

Acquired hernias can occur in any breed of dog or cat. The cause is unknown but it is suspected to result from disorders that cause increases in intra-abdominal pressure (ie chronic vomiting) or increases in negative intrathoracic pressure (ie intermittent airway obstruction seen with laryngeal paralysis).

Diagnosis

Clinical Signs

Some animals may be asymptomatic but otherwise clinical signs include:

• regurgitation
• vomiting
• hypersalivation
• dyspnoea
• coughing
• dehydration
• weight loss

Diagnostic Imaging

• Plain survey radiographs may visualise a caudodorsal gas-filled intrathoracic soft tissue opacity which is diagnostic of a hiatal hernia.Oesophageal dilatation and alveolar consolidation may be present with aspiration pneumonia.
• Barium contrast studies may be used to confirm a diagnosis.

Intermittent hiatal hernias can be difficult to detect and therefore it is sometimes necessary to put pressure on the abdomen during the radiography procedure to induce displacement of the stomach.

• Fluoroscopy can be used to assess for intermittent herniation if a hiatal hernia is suspected by the survey radiographs.
• Endoscopy may demonstrate cranial displacement of the caudal oesophageal sphincter and a large oesophageal hiatus.

Treatment

Medical therapy should be attempted first:

The suspected cause (ie.Oesphagitis)should be corrected first. Oral feedings should be withdrawn in patients with severe stricture or oesophagitis. An oesophagostomy tube may be placed in these cases to provide nutritional support.

Medical therapies:

• Oral sucralfate
• Gastric acid secretory inhibitors (cimetidine, ranitidine, omeprazole)
• Anti-inflammatory doses of corticosteroids (prednisolone) to prevent fibrosis and re-stricture.

Surgical therapies:

• Dilation/widening of the stricture by ballooning or bougienage.
• Surgical resection is not recommended because iatrogenic strictures at the anastomotic site are possible.

Prognosis

The shorter the length of oesophagus involved and the quicker the corrective procedure is performed the better the prognosis. Animals with large, mature strictures and those with continued oesophagitis have a guarded prognosis. Long term gastrostomy tubes may be required in some cases.

References

• Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA

• Merck & Co (2008) The Merck Veterinary Manual

• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.