Diaphragmatic Hernias in Dogs and Cats

What is a diaphragm and what does it do?

The diaphragm is a thin layer of muscle that separates the chest cavity from the abdominal cavity, including the organs in each compartment (heart and lungs in the thoracic space and abdominal organs such as the liver, stomach, and intestine).

It also helps with breathing and contracts to help increase the pressure in the abdomen during defecation or urination. Therefore, problems associated with the diaphragm can lead to compromised breathing or difficulty in passing stool or urine.

What is a diaphragmatic hernia?

A hernia is a condition described by the protrusion of an organ from one part of the body to another through a gap or opening. Dogs and cats can develop different hernias in their body and the severity can vary widely from mild, asymptomatic hernias to those that can be life-threatening if not addressed immediately.

A diaphragmatic hernia occurs when an opening in the diaphragm allows abdominal organs to protrude into the chest cavity. Both dogs and cats can develop a diaphragmatic hernia, and most cases usually involve the stomach and a portion of the intestine protruding through the gap in the animal’s diaphragm.

There are generally two types of diaphragmatic hernia in dogs and cats: traumatic and congenital. Most cases of diaphragmatic hernia in both dogs and cats are congenital, which means they are born with some degree of defect in their diaphragm, allowing abdominal organs to protrude into the thoracic (chest) cavity.

One particular form of congenital diaphragmatic hernia, called a peritoneal-pericardial diaphragmatic hernia (PPDH), occurs due to a defect in the development of the fetus. PPDH occurs in both puppies and kittens and is described as a defect in the diaphragm that forms a connection between the abdomen and the pericardial cavity (the space between the pericardium (heart sac) and the heart). In this type of diaphragmatic hernia, abdominal organs are free to move to and from the abdominal cavity and the pericardial space, which causes significant clinical signs related to the animal’s breathing and heart function.

Traumatic diaphragmatic hernias are caused by a forceful blunt trauma, usually directed to the pet’s abdomen. This causes an increase in abdominal pressure which results in a rupture in the diaphragm and herniation of abdominal organs and tissues to the thoracic cavity. On rare occasions, trauma can also cause the formation of PPDH in both dogs and cats.

What is a hiatal hernia?

Hiatal hernias specifically involve the protrusion of a portion of the stomach or the intestine from the abdomen into the chest cavity through an opening in the diaphragm called the hiatus. This opening is designed to accommodate only the esophagus to allow the transit of food from the mouth to the stomach.

When the muscles surrounding the hiatus become weak, the opening starts to expand, allowing the upper part of the stomach to bulge through the diaphragm and into the chest cavity. In severe cases, the hiatus becomes big enough that portions of the small intestine also protrude through the diaphragm.

In most cases, the protrusion is temporary and the stomach slides in and out of the opening back and forth the abdomen and chest cavity. In more severe cases, the stomach or a part of the intestine can be permanently displaced, causing health problems for the animal.

Symptoms of a Diaphragmatic Hernia in Dogs and Cats

Clinical signs associated with a diaphragmatic hernia in pets depend on the extent of the tear or gap on the diaphragm and the extent of herniation of abdominal tissues. Displacement of abdominal organs into the chest cavity leads to incomplete inflation of the lungs during breathing, or, in the case of a peritoneal-pericardial diaphragmatic hernia, the improper beating of the heart.

Dogs and cats with diaphragmatic hernia will often present with persistent coughing, poor appetite, weakness, and lethargy. In severe cases, affected animals will have breathing difficulties or have a rapid short breathing pattern, fever, and collapse.

Persistent vomiting and regurgitation are also common signs seen in dogs and cats with a diaphragmatic hernia. When abdominal organs become trapped in the thoracic cavity, their blood supply gets cut, off resulting in a wide range of digestive symptoms. Abdominal discomfort and pain may also be present depending on how extensive the herniation is and how chronic the condition has been.

Persistent vomiting and regurgitation also increase the chance of complications such as aspiration pneumonia. Dogs and cats with pneumonia secondary to a diaphragmatic hernia will have severe breathing difficulties along with fever and decreased appetite.

Dogs and cats with a mild diaphragmatic hernia can live with the condition for years without showing clinical signs. In more severe cases, symptoms can be life-threatening, especially if not treated or addressed immediately.

How are diaphragmatic hernias diagnosed?

Diagnosis for diaphragmatic hernias are based on physical exam, clinical signs, medical history, and diagnostic imaging. Your vet will rule out the possibility of diaphragmatic hernia if clinical signs fit and will request tests to confirm the diagnosis.

In most cases, radiographs are often sufficient enough to arrive at a definitive diagnosis. If herniation of abdominal contents is extensive, it will be evident from the chest and abdominal radiograph images. Other diagnostic imaging methods such as ultrasound or contrast imaging can help support the diagnosis if radiographs are inconclusive.

If you start to observe any of the symptoms mentioned above in your pet, it’s best to schedule an appointment with your veterinarian right away for a thorough check-up to rule out the possibility of a diaphragmatic hernia.

Treatment Options for Pets with a Diaphragmatic Hernia

The only treatment for diaphragmatic hernia in dogs and cats is surgical correction. Your vet may refer you to a veterinary surgical specialist who will correct the displacement of abdominal organs and patch up the gap or tear in the patient’s diaphragm to prevent a recurrence.

Diaphragmatic hernia repair is a risky procedure since the surgery involves the diaphragm, an organ that plays an important role in the breathing of the patient. Complications can lead to severe breathing problems even if the tear has been repaired. This is the reason why most veterinarians will hold off surgical correction in dogs and cats that have an asymptomatic diaphragmatic hernia (not showing any symptoms).

Pets with a mild diaphragmatic hernia can live for years without showing any clinical signs or developing complications. Those that have undergone successful hernia repair without complication also have a very good prognosis with slim chances of recurrence.

Read more:

Umbilical Hernias in Dogs and Cats

Your Pet’s Heart: A Guide to Understanding Heart Health in Dogs and Cats

First Aid & Emergency Care for Breathing Problems in Pets

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