Abnormal Diaphragm Opening in Cats

By PetMD Editorial on Dec. 19, 2008

Diaphragmatic Hernia in Cats

Diaphragmatic hernias occur when an abdominal organ (such as the stomach, liver, intestine, etc.) moves into an abnormal opening in the cat's diaphragm, the sheet of muscle separating the abdomen from the rib cage area. This can occur because of an acquired injury from a forceful blow, such as a car accident, or because of a defect at birth (congenital).

The condition or disease described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects dogs please visit this page in the PetMD health library.

Symptoms and Types

Signs of a diaphragmatic hernia include irregular heartbeat, labored breathing (especially after a forceful blow) and symptoms of shock. The abdomen may move rapidly (palpitate) or feel empty. Reactions such as vomiting, diarrhea, and bloating can occur because of damage to the bowel or stomach.

In congenital cases, the symptoms may not be evident immediately. Gradual symptoms include muffled heart sounds or heart murmurs, abdominal defects, and trouble breathing. Signs may occur suddenly with damage to the bowel, spleen, or liver.


Most commonly, diaphragmatic hernia is caused by a trauma such as being hit by a car or other forceful blow. Therefore, diaphragmatic hernias occur most commonly with roaming outdoor cats. The pressure of such an impact causes a tear in the diaphragm, allowing an internal organ to protrude through the rip.

The reason for congenital diaphragmatic hernias is not known, although certain breeds are more likely to develop this abnormality. Some breeds may be predisposed, Himalayan cats in particular show higher numbers of congenital diaphragmatic hernias. Other birth defects may be evident in cats born with a diaphragmatic hernia, and the condition may cause further problems including rib fractures, organ failure, and impaired lung expansion.



The most useful diagnostic test is through the use of X-rays (radiographs) to reveal inner abnormalities. If this is insufficient, further imaging processes like ultrasounds may be used.

Other symptoms that initially appear to be caused by a diaphragmatic hernia include a gathering of excess fluid in the space around the lungs or abnormally fast breathing due to other causes.

Treatment and Care

For trauma-induced diaphragmatic hernias, the patient must be treated for shock and it is imperative that breathing and heart rate are stabilized before going into surgery. Surgery should repair damaged organs, as well as the tear in the diaphragm. It is important that the patient be stable before surgery begins, as surgery will not necessarily improve any heart or breathing problems.

For congenital diaphragmatic hernias, surgery should be performed as soon as possible in order to avoid further damage to the animal’s internal organs. Again, it is important that breathing and heart rate are stabilized before operating. Drugs can be used to help stabilize heart rate.


Living and Management

After surgery is complete, there are secondary problems to look out for. Monitoring of heart rate with a monitor (electrocardiograph) is advised to check for irregular heartbeat.

Hyperthermia, or increased body temperature, is common in cats after surgery. Another common problem is swelling or fluid accumulation in the lungs (pulmonary edema).

Most animals survive when surgery is successful and all secondary effects are controlled. Older cats with trauma-induced hernias are less likely to survive surgery.



There is no method to prevent congenital diaphragmatic hernias, although it is best to operate as soon as possible. To avoid traumatic experiences that may cause diaphragmatic hernias, it is best to keep pets away from potentially dangerous areas, such as streets where car accidents are likely to occur.

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