Diaphragmatic Hernia in Dogs

Melissa Boldan, DVM
By Melissa Boldan, DVM on Aug. 4, 2023
dog getting an xray at vet hospital

In This Article


What Is a Diaphragmatic Hernia in Dogs?

The diaphragm, a thin muscle, serves as a vital barrier, separating the chest cavity from the abdominal cavity in dogs. Its role in the breathing process is crucial: during inhalation, the diaphragm flattens, generating a vacuum that draws air into the expanding lungs. Upon exhalation, the diaphragm returns to its normal dome shape, facilitating the expulsion of air from the body.

However, if the diaphragm muscle becomes torn, a concerning condition can arise. This tear allows the contents of the abdomen to breach into the thoracic (chest) cavity. In essence, the dog’s stomach, intestine, and other organs can migrate into the chest, where they don’t belong. This condition is known as a diaphragmatic hernia or, alternatively, a herniated diaphragm.

Diaphragmatic hernias in dogs primarily occur due to blunt force trauma, often resulting from incidents like a dog being hit by a car or kicked by a large farm animal. This forceful impact causes a tear in the thin diaphragm muscle. The size of the tear can vary, ranging from very small and easily sealed with abdominal tissue, called mesentery, to significantly large. In some cases, the tear may start as a very small opening and enlarge over time.

This condition is commonly screened for by veterinarians when there is a known history of trauma. It is generally regarded as a medical emergency, except in cases where the tear is very small and the dog remains otherwise stable. Prompt diagnosis and appropriate treatment are crucial in managing diaphragmatic hernias to ensure the best possible outcome for the dog.

Symptoms of a Diaphragmatic Hernia in Dogs

  • Vomiting
  • Difficulty breathing

  • Rapid, shallow breaths

  • Cyanotic (blue) gums

  • Anorexia (loss of appetite)

  • Exercise intolerance

  • Muffled heart sounds

  • Thinner, empty-looking abdomen

  • In some cases, there may be no signs at all, making the condition even more challenging to detect without thorough medical evaluation

Causes of a Diaphragmatic Hernia in Dogs

The most frequent cause of a diaphragmatic hernia in dogs is trauma. Common examples of traumatic incidents include being hit by a car, kicked by a cow or horse, or falling from a high ledge or out of a window. The sheer force from such events can lead to a tear in the thin muscle that separates the chest from the abdomen.

In rare instances, a dog may be born with a congenital diaphragmatic hernia, where there is a defect present at birth.

How Veterinarians Diagnose a Diaphragmatic Hernia in Dogs

Diaphragmatic hernias are most commonly diagnosed by X-rays after a physical exam. Your veterinarian should be able to visualize the normal diaphragm and confirm that the chest and abdomen appear normal, with everything in its proper place.

Sometimes, the tear in the diaphragm is so small that it can be missed on initial X-rays. If there is a history of trauma, your veterinarian may recommend follow-up X-rays or special imaging to clarify whether a hernia is present.

The ease of diagnosing the hernia depends on the size of the initial tear in the diaphragm. If there are no signs detected during your dog’s initial exam and X-rays but a hernia is present, several months may pass before small amounts of abdominal tissue start to slide and protrude through the hole. This can exert pressure on the tear, enlarging it. Eventually, more abdominal organs, such as the intestines, stomach, and liver, may herniate through the hole and enter the chest.

Your dog may display signs of a hernia much later after the traumatic event, necessitating repeat X-rays to diagnose the diaphragmatic hernia accurately.

Treatment of a Diaphragmatic Hernia in Dogs

Diaphragmatic hernias are typically treated surgically. Depending on the severity of the hernia, your dog may need to be stabilized before undergoing anesthesia for the surgical repair of the torn diaphragm.

In situations where fluid from the abdomen has entered the chest cavity, hindering your dog’s ability to breathe, your veterinarian may recommend a procedure known as thoracocentesis before the surgery. This involves removal of fluid from the chest cavity using a needle, allowing the lungs to expand and enabling the dog to breathe more easily.

Unfortunately, diaphragmatic hernias cannot be treated with medications, and surgery remains the most effective course of action. Before proceeding with surgery, it is crucial that a dog is stable. However, delaying surgery for too long can result in formation of scar tissue between the lungs and abdominal organs, making surgery a risky option.

Early intervention is key to preventing complications and improving the chances of a successful outcome. The veterinary surgeon will carefully assess your dog’s condition and determine the optimal timing for surgery, balancing the need for stabilization with the potential risks of delay. By promptly addressing the diaphragmatic hernia through surgery, they can provide the best possible chance of recovery for your dog.

Recovery and Management of Herniated Diaphragm in Dogs

The prognosis for dogs after surgery to repair a herniated diaphragm is typically guarded for the first 24 hours. Some dogs may experience re-expansion edema, the accumulation of fluid in their lungs after the hernia has been repaired. This condition is usually seen when the lung lobes have collapsed for an extended period while the hernia was present.

However, if your dog is doing well after the initial 24 hours, their prognosis for a full recovery improves significantly.

It is crucial to follow all post-operative instructions during your dog’s recovery from surgery. The recovery period typically lasts for about two weeks and necessitates strict rest and activity restriction.

When taking your dog outside, be sure to leash-walk them only and avoid letting them run, jump, or engage in play during this time. To prevent licking, chewing, or scratching at the incision, your dog should wear an Elizabethan collar or recovery shirt whenever they are not under direct supervision until the sutures or staples are removed.

Administer all prescribed pain medications and antibiotics as directed on their labels. If during the recovery period you notice any signs of concern, such as difficulty breathing, lethargy, vomiting, or decreased appetite, contact your veterinarian promptly.

Diaphragmatic Hernia in Dogs FAQs

Can dogs live with a herniated diaphragm?

While a diaphragmatic hernia should be surgically repaired as soon as possible, dogs may be able to live with a hernia for a period of time, depending on its size and severity.

How common are herniated diaphragms in dogs?

Diaphragmatic hernias are relatively uncommon injuries in dogs. However, dogs who experience blunt force trauma should be screened by a veterinarian for a herniated diaphragm.

Featured Image: iStock.com/urbancow

Melissa Boldan, DVM


Melissa Boldan, DVM


Dr. Melissa Boldan graduated from the University of Missouri College of Veterinary Medicine in 2012. She initially practiced mixed animal...

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