What is a diaphragmatic hernia?
The diaphragm is a muscular and tendinous structure that separates the abdomen from the chest and helps with breathing. A hernia is present when there is a hole in the diaphragm.
The most common cause of diaphragmatic hernia in dogs and cats is trauma, most commonly after being hit by a car. When a large force is applied to the abdominal cavity, and the animals throat is open, this creates a large increase in abdominal pressure and forces a hole in the diaphragm. Animals can also be born with a diaphragmatic hernia though it is not common for these to require surgery.
How is this condition diagnosed?
In every patient that has had a traumatic injury, we suspect a diaphragmatic hernia. Sometimes these animals present with difficulty breathing, but at times your pet will be showing no signs.
Some animals may have no specific clinical examination findings. Other findings can include a tucked up abdomen (as the organs have moved into the thorax), muffled or abnormally positioned heart sounds, difficulties breathing, difficulty lying down, or standing with their legs apart and head extended.
Radiography is the most useful tool for diagnosing diaphragmatic hernia. This enables us to see a discontinuation in the diaphragm, and often we will see abdominal organs in the chest cavity. Ultrasound can also be used to assess the diaphragm for any defects. These days, CT imaging is also used to assess the diaphragm as well as the rest of the chest and abdomen for any concurrent injuries.
How is a diaphragmatic hernia treated?
Before your pets diaphragmatic hernia can be treated, we must make sure that we identify all other injuries your pet may have, and make sure they are stable enough to be placed under a general anaesthetic. As diaphragmatic hernias are often the result of vehicular trauma, your pet may have a number of other injuries, and will likely present to us in shock. We may need to stabilise your pet with pain relief and intravenous fluids and perform additional imaging to identify any other injuries. Only when your pet is stable enough will we perform surgery to repair their diaphragm.
Surgery involves making an abdominal incision and pulling all the organs back from the thorax into the abdomen. During this procedure we must ventilate (breathe for) your pet, as there is a direct opening from the chest to the outside world. After the organs have been placed back where they belong, the diaphragm is sutured closed. We then make sure that we check all your pets organs to ensure that there has been no damage, and close the abdomen.
A chest tube will be placed into your pets chest to get rid of any excess fluid and air. This will usually stay in place for a couple of days, but will be removed before your pet goes home from hospital.
What is the prognosis?
The prognosis is good for animals that have no (or only minor) other injuries. In most cases it is better to repair these hernias early but some patients require stabilization for up to a week prior to corrective surgery to allow the lungs or other body systems to heal first.