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==Typical Signalment==

==Introduction==  

A hiatal hernia is an abnormality of the diaphragm that allows part of the stomach and the abdominal oesophagus to displace into the thoracic cavity. Two types of hiatal hernia have been recognised in the dog and cat:

:'''Sliding hiatal hernia''' (type I) - Cranial displacement of the distal oesophagus and stomach into the mediastinum through the oesophageal hiatus of the diaphragm.  This is the most common form and it can occur in the dog and cat as a congenital or acquired lesion. Congenital hernias result from the incomplete fusion of the ''septum transversum'' (which forms the diaphragm) during early embryonic development.

:'''Para-oesophageal''' or '''Rolling hiatal hernia''' (type II) - Cranial displacement of the gastric fundus into mediastinum through the oesophageal hiatus but adjacent to the oesophagus and gastric cardia which remain in their normal positions.  This form of hernia is rare in animals.

==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:

*'''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 and these often occur with disorders that cause increases in intra-abdominal pressure (such as chronic vomiting) or decreases in intrathoracic pressure (such as intermittent airway obstruction seen with [[Laryngeal Paralysis|laryngeal paralysis]] and [[Brachycephalic Airway Syndrome|brachycephalic obstructive airway syndrome]] (BOAS)).  

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).  

Breeds of dog that develop '''congenital''' sliding hernias include Chinese Shar-peis and Chow-chows whereas brachycephalic dogs (such as English and French bulldogs) often develop acquired hernias.

==Diagnosis==

==Diagnosis==

===Clinical Signs===

===Clinical Signs===

Some animals may be asymptomatic but otherwise clinical signs include:

Some animals may be asymptomatic but otherwise clinical signs include:

 

 

*coughing

 

'''Dyspnoea''' and '''coughing''' if the hernia is large and impinges on the lungs or if the animal develops aspiration pneumonia as a result of regurgitation

*weight loss

 

'''Dehydration''' and '''weight loss''' due to chronic regurgitation

 

===Diagnostic Imaging===

===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.

'''Plain survey radiographs''' may show a gas-filled soft tissue opacity in the caudodorsal thorax, continuous with the diaphragmatic margin. Secondary [[Megaoesophagus|megaoesophagus]] may develop in longstanding cases and an alveolar lung pattern may be apparent, especially cranio-ventrally, if the animal is developing 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 radiography to induce displacement of the stomach.

*'''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.

'''Fluoroscopy''' can be used to identify cases of intermittent herniation if the condition is still suspected after plain radiography.

*'''Endoscopy''' may demonstrate cranial displacement of the caudal oesophageal sphincter and a large oesophageal hiatus.

 

'''Endoscopy''' may demonstrate cranial displacement of the lower oesophageal sphincter and a large oesophageal hiatus.

==Treatment==

==Treatment==

Medical therapy should be attempted first:

===Medical Management===

Medical therapies:

Medical management should be initiated to reduce [[Oesophagitis|oesophagitis]] caused by regurgitation.  Medical management can be continued for cases with acquired hernias and it may achieve success in some cases with congenital hernias.  This approach involves the use of:

*Oral sucralfate

:'''[[Gastroprotective Drugs]]''' including oral sucralfate suspensions and gastric acid secretory inhibitors such as cimetidine, ranitidine or omeprazole.

*Gastric acid secretory inhibitors (cimetidine, ranitidine, omeprazole)

:A '''low fat diet''' fed from a height will increase the tone of the lower oesophageal sphincter and increase the speed of gastric emptying, reducing the likelihood of regurgitation.

*Anti-inflammatory doses of corticosteroids (prednisolone) to prevent fibrosis and re-stricture.

:'''Metaclopramide''' may also be used to increase the tone of the lower oesophageal sphincter.

:'''Antibiotics, nebulisation and coupage''' may be used to manage aspiration pneumonia.

Surgical therapies:

===Surgical Management===

Surgical management can be used with congenital cases (after medical management has been attempted) and to treat the underlying cause in acquired cases.

*Surgical resection is not recommended because iatrogenic strictures at the anastomotic site are possible.

==Prognosis==

==Prognosis==

The shorter the length of oesophagus involved and the quicker the corrective procedure is performed the better the prognosis.

Prognosis is good after surgical repair or aggressive medical management, but complete relief of clinical signs may not be possible.

Animals with large, mature strictures and those with continued oesophagitis have a guarded prognosis. Long term gastrostomy tubes may be required in some cases.

 

|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis00644.asp, Hiatal hernia]<br>[https://www.vetstream.com/canis/Content/Illustration/ill00366.asp, Hiatal hernia - barium contrast]<br>[https://www.vetstream.com/canis/Content/Illustration/ill00365.asp, Hiatal hernia - radiograph]

|literature search = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=Hiatal+&occuring1=title&rowId=2&options2=AND&q2=Hernia&occuring2=title&rowId=3&options3=AND&q3=&occuring3=freetext&x=55&y=10&publishedstart=yyyy&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all Hiatal Hernia publications]

==References==

==References==

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

[https://www.vetstream.com/canis/Content/Disease/dis00644.asp]