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CONTRIBUTOR(S): Zoe Halfacree, Vetstream Ltd, Fear Free,

Diaphragmatic hernias

Diaphragmatic hernias

There are several types of hernia (also known as a rupture) seen in the dog and the causes vary between the different types. Some hernias can be minor, but in certain circumstances they can be very serious and often require surgical treatment.

Thorax: diaphragmatic hernia 02 – ultrasound ©Avi Avner & Andrew Holloway

What is a hernia?

A hernia is a swelling caused by structures from the abdomen bulging out through the muscle wall. The structures may escape by stretching a natural opening such as in an umbilical hernia, or come through a defect in the muscle wall that has developed due to old-age or trauma. The swelling may appear as a lump under the skin on the abdomen (umbilical, inguinal) or beside the anus (perineal). Typically, the swelling contains some fatty tissue, but in some cases abdominal organs (most commonly sections of bowel) could be present.

Sometimes hernias form between the deeper muscle layers so the swelling is not obvious when looking from the outside. These may go unrecognized until your dog becomes unwell due to entrapment of a vital structure. Signs could include bringing up food/regurgitating for hiatal hernias or rapid or difficulty breathing with diaphragmatic hernias.

What is a diaphragmatic hernia or rupture?

In a normal animal the chest cavity and the abdomen are separated by a continuous sheet of muscle – the diaphragm. A diaphragmatic hernia or rupture is where contents from the abdomen pass through an opening or defect in the diaphragm into the chest cavity.

A diaphragmatic rupture is much more common than a diaphragmatic hernia; it is caused by trauma, such as a blunt blow to the abdomen by a car accident or a fall, causing a tear in the diaphragm muscle. When the diaphragm tears, abdominal contents can pass into the chest and this makes it hard for the lungs to fill with air. This is a true emergency and once your pet has been stabilized an operation will be needed to repair the damage. If your pet has experienced a fall or been hit by a car they should always be examined by a veterinarian. Your veterinarian will recommend further tests (x-rays or ultrasound) if they have concerns on examination.

A true diaphragmatic hernia is a rare abnormality that your pet is born with. During development the diaphragm may not completely close, allowing some communication between the abdomen and the chest. The most common form is a pericardial peritoneal diaphragmatic hernia (PPDH) in which there is communication between the abdomen and the sac around the heart. In some cases, abdominal contents (often bowel) move into this sac and this may interfere with heart function. However, some animals with PPDH may live with the condition and have a good quality of life and the problem may not be picked up until later on in life. Puppies with clinical signs may have rapid breathing, poor exercise tolerance and occasional vomiting. A diagnosis can be made by chest x-ray. This type of hernia is not always treated with surgery; it may be best left untreated if it is not causing obvious signs and has only been picked up when performing another check.

What is a hiatal hernia?

Although the diaphragm separates the abdomen from the chest cavity some structures need to pass from chest to abdomen (such as the esophagus which carries food from the mouth to the stomach) and have to pass through the diaphragm. This means there are natural holes (hiatus) in the barrier. A hiatal hernia is the protrusion of abdominal organs through the hiatus of the diaphragm into the thoracic cavity, most commonly through the hole the esophagus passes through. Abdominal organs can move alongside the esophagus and into the chest. Dogs with a hiatal hernia may regurgitate their food intermittently. Typically, the tissues passing through the hole move back and forth with breathing. In most cases a tiny portion of the stomach enters the chest but the signs are caused by the acid refluxing from the stomach and damaging to the soft lining of the esophagus. Occasionally other organs, such as small intestine or spleen, can also pass into the hiatus and can become trapped. There is a strong breed association with this condition because it is related to the dog’s shape or conformation. Some breeds of dogs, especially Shar Peis and Bulldogs, are more likely to be affected. Short-nosed dogs (brachycephaly) experience high resistance to airflow as they breathe in so they have to make extra effort as they breathe. This puts pressure on the esophageal hiatus making any herniation worse. The treatment for this type of hernia always involves treatment of the brachycephalic obstructive airway syndrome (BAOS) as well as repairing the esophageal hiatus and fixing the stomach in the abdomen so that it cannot move. After surgery a feeding tube is used to provide nutrition.

How will I know if my dog has a hernia or rupture?

There is often no external sign that there is a problem. Dogs with diaphragm hernias or ruptures may have problems with breathing or start bringing up food.

How will my veterinarian diagnose my dog’s hernia/rupture?

Your vet may be able to detect an abnormality on examination or may need to perform further tests to make the diagnosis. These include x-rays of the abdomen and or chest and also possibly an ultrasound. In some circumstances a Computed Tomography (CT) scan may be chosen if it is available and additional information is considered beneficial.

How are hernias/ ruptures treated?

Diaphragm rupture always requires surgical correction to prevent serious complications. Before surgery your dog will remain in hospital as they could deteriorate rapidly. Surgery is performed as an urgent or emergency surgery, depending upon how stable your dog is and what other injuries they may have. Under general anesthetic the abdomen is opened so that the hole in the diaphragm can be seen. The displaced organs can be gently returned to the abdomen and inspected for injury; the diaphragm muscle can then be repaired.

It is not always necessary to operate to repair a true diaphragmatic hernia. Sometimes it is picked up as a surprise finding during a check-up for another reason. However, if your pet is having problems associated with the hernia then surgery may be advised. During surgery the opening through which the esophagus passes is made smaller, and the esophagus and the stomach are fixed in their correct locations and a feeding tube is placed. The feeding tube is only temporary but should remain in for 14 days so your puppy will usually come home with the feeding tube in place. It is important that they are not allowed to interfere with the tube.

How can I prevent my dog getting a hernia/ rupture?

Diaphragmatic rupture occurs as a result of trauma and therefore avoiding a traumatic event can prevent this from occurring.  You should keep your dog on a lead during risk times, however accidents can happen at any time.

Diaphragmatic hernias are present from birth and there is nothing you can to do prevent them from occurring. There is a strong breed link to brachycephalic breeds for hiatal hernia so if you choose to have a puppy from one of these breeds you should be aware of the potential for the condition to develop.

What problems may occur after my dog’s hernia surgery?

There is a risk with any surgery of bleeding, wound infection and wound breakdown. With a hernia there is also the risk of recurrence. It is important to monitor for signs of bleeding, swelling of the area around the wound, recurrence of swelling beneath the wound and wound discharge. If you see any of these please speak to your veterinary surgeon for advice.

The wound itself is left open to the air after surgery and should be kept clean and dry. If you are concerned that the wound is dirty contact your veterinarian before bathing the wound as the risk of infection is higher if the wound is wet. Your dog, and other pets, should be prevented from interfering with the wound. You must use a buster collar, post-op coat or T-Shirt to prevent interference and keep other pets away from your dog when you are not supervising interactions.

After surgery you should watch your dog closely to see that they are showing normal behaviors such as passing urine and feces normally and have a good appetite. Let your veterinarian know if you have any concerns. It is quite common for a dog to develop a slight dry cough for a couple of days following an anesthetic due to the endotracheal tube causing irritation and this should resolve quickly. A moist/productive cough is suggestive of pneumonia, which can occur following any anesthetic but is more likely if there is another predisposing factor, such as regurgitation which occurs in hiatal hernia.

Your dog’s exercise should be restricted during the recovery phase, until your veterinarian has completed a post-operative check and is happy with the healing. Your dog must remain on the lead at all times for the first 10 days, even when taken to the garden for toilet purposes. Your veterinarian will give you specific instructions regarding the return to a normal level of exercise; typically on lead exercise must continue for a further 4 weeks with a gradual increase in length of walk each day.

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