What is a diaphragmatic hernia?
The diaphragm is the muscular partition that separates the abdomen and the chest. Tearing or disruption of this thin muscle is called a diaphragmatic hernia or diaphragmatic rupture.
One form of diaphragmatic hernia, peritoneal-pericardial diaphragmatic hernia (PPDH), is congenital (present from birth) and may be due to defective development of the fetus.
With this condition, there is an opening between the abdomen and the pericardium (the protective sac around the heart). This condition is most often found in puppies or kittens and should be considered separately from the traumatic type of diaphragmatic hernia or rupture.
Once a tear in the diaphragm is present, abdominal contents such as the stomach, liver, and intestines may enter the chest cavity. The abdominal contents compress the lungs and prevent them from fully inflating, causing respiratory distress, (difficulties breathing). The abdominal tissue may irritate the heart muscle, which may cause abnormal heart rhythms. Fluid may leak into the chest cavity, further complicating and worsening heart and lung function.
What causes a diaphragmatic hernia or rupture?
The most common cause of diaphragmatic hernia is blunt force trauma. This type of trauma can occur after a fall from a high place (such as out of a window), an automobile accident, or a blow to the abdomen. Congenital diaphragmatic hernias are less commonly seen.
What are the clinical signs of diaphragmatic hernia?
Clinical signs are dependent on the severity of herniation. With small tears or in cats born with a diaphragmatic hernia, there may be no discernible clinical signs. Many pet owners report mild breathing difficulties, especially when the cat is stressed, and periods of mild gastrointestinal upset. In severe or acute cases, there is often respiratory distress, an abnormal heart rhythm, muffled heart and lung sounds, and other signs of systemic shock. The abdomen may feel empty when palpated.
How is a diaphragmatic hernia diagnosed?
Diagnosis is based on medical history, physical examination findings, and X-rays (radiographs). Blood and urine tests may be performed if the patient is showing signs of shock. In certain cases, ultrasound or special radiographic dye studies will be required for a definitive diagnosis.
What is the treatment for a diaphragmatic hernia?
Treatment is first directed at stabilizing the cat if trauma has recently occurred. Some patients will require immediate thoracocentesis (a chest 'tap') to remove any fluid that has accumulated in the chest cavity. Once the patient is stable, the hernia must be corrected surgically. This surgery is often done in referral centers by surgical and anesthesia specialists. In congenital forms, surgical intervention as early as possible is important to prevent organ entrapment or scarring between the intestines and the chest cavity. Many congenital diaphragmatic hernias are discovered during spaying (ovariohysterectomy) and may be corrected at that time.
What is the prognosis?
The prognosis for any patient with diaphragmatic hernia is always initially guarded. It improves if the patient has been stabilized and the heart rhythm is normal. After surgery, the risk of a condition called re-expansion pulmonary edema may occur, in which fluid can fill the lungs. Therefore, a guarded prognosis must be given for at least 24 hours after any surgery. The prognosis for a young kitten with a congenital diaphragmatic hernia is guarded to good, depending on the specific diaphragmatic defect and the abnormalities found during surgical correction.
If the patient stabilizes with medical treatment, is it possible to avoid surgery?
In trauma cases, adhesions may form between the lungs and any herniated abdominal contents after approximately seven days. These adhesions will affect the ability of the lungs to inflate properly. The longer the corrective surgery is delayed, the more complicated and dangerous it becomes. However, each case needs to be assessed individually.
