A Primer on Diaphragmatic Hernia in Dogs

The diaphragm is a muscular partition that separates the abdomen and the chest. A tear in this thin muscle is called a diaphragmatic hernia or rupture.

A Primer on Diaphragmatic Hernia in Dogs

What causes it?

The most common cause of diaphragmatic hernia is blunt trauma, such as being hit by a car or falling from a high place.  

Puppies can develop a congenital diaphragmatic hernia that results from defective development of the fetus.

What happens with a hernia?

Once the diaphragm is torn, abdominal contents can enter the chest cavity.  

This compresses the lungs and prevents them from fully inflating, causing respiratory distress.  The abdominal contents can also press against the heart and cause abnormal heart rhythms. In addition, fluid can leak into the chest cavity, worsening heart and lung function.

What does it look like?

Signs depend on the size of the tear and the amount of abdominal contents that move up into the chest cavity. 

There may be no apparent signs of small tears and most congenital hernias.  However, in most cases, the dog may have breathing difficulties, especially during stress or exercise, and mild gastrointestinal upset.  The dog may have much more trouble breathing and abnormal heart rhythms in severe cases.

Diaphragmatic hernia diagnosis

Diagnosis is based on history, physical examination, and x-rays.  Some cases require ultrasound or special x-ray dye studies.

Treatment requires surgical repair. In cases of recent trauma, the dog must be stabilized before the hernia can be corrected.  Prognosis after surgery is initially guarded because of the seriousness of the operation and the risk of complications.

Congenital hernias in females are often discovered and repaired when the dog is spayed.

Related articles:
When Is It an Emergency?

Further reading:
Hernia (Diaphragmatic) in Dogs

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