The pericardium is a membrane that surrounds the heart. It consists of two layers: a visceral layer (epicardium) that is tightly adherent to the heart muscle and an outer parietal layer. Between these two layers is a potential space, the pericardial space, which normally contains a small amount of fluid. The pericardium is inelastic and does not distend easily. When excessive fluid accumulates within the pericardial space, the heart loses its ability to beat normally and serious illness can occur.

Several illnesses can affect the pericardium. These include peritoneopericardial diaphragmatic hernia, pericardial effusion, and constrictive pericardial disease.

Peritoneopericardial Diaphragmatic Hernia

This type of hernia is present from birth. Affected dogs are born with an abnormality of the diaphragm, which allows abdominal contents to slip into the surrounds the pericardial space. In dogs, the hernia more often contains loops of intestine.

Pericardial Effusion

Pericardial effusion is a term used to describe an accumulation of fluid within the pericardial space. Different types of fluid, including clear fluid, pus, or blood, may accumulate. As fluid accumulates, the heart's action is compromised as fluid pressure builds up on account of the inability of the pericardial sac to distend. Eventually, the heart is unable to adequately pump blood to the body and the dog may collapse. Without emergency treatment, death is imminent.

Constrictive Pericardial Disease

Pericardial constriction most often develops secondary to chronic inflammation, particularly as a result of infective disease of the pericardium, or recurrent hemorrhage. Rarely, calcium deposits thicken the pericardium. In chronic inflammation, the pericardial space may become obliterated and the heart encased in a rigid, poorly expansive sac. As the fluid is reabsorbed, the pericardium scars and contracts, and consequently the chambers of the heart become constricted and cannot expand effectively. This condition limits the heart's ability to pump blood and can lead to right-sided heart failure.

What to Watch For

Weakness

Collapse

Difficulty breathing

Pale gums

Lack of appetite

Diagnosis

Blood work is often performed to determine the overall health of the animal. Usually, the blood work is normal, but some animals may be anemic or have other abnormalities.

Chest radiographs (X-rays) are performed to determine if the size and shape of the heart.

Ultrasound of the heart (echocardiogram) is performed both to confirm pericardial disease and determine the type.

Treatment

Treatment varies depending on the type of pericardial disease.

Peritoneopericardial diaphragmatic hernia is often an incidental finding and usually does not cause obvious illness. In such cases, the dog should be observed over time for signs of developing illness. For dogs that have clinical signs of disease associated with peritoneopericardial diaphragmatic hernia, surgery is the only treatment.

Pericardial effusion may be treated by removing fluid that has accumulated in the pericardial sac. In addition, attempts should be made to address the inciting cause of the fluid accumulation.

Constrictive pericardial disease is treated with surgical removal of the pericardium.

Home Care and Prevention

There is no home care for pericardial disease. If you suspect that your dog has pericardial disease, consult your veterinarian. Prevention of pericardial disease is difficult and often not possible. Early diagnosis and treatment can help reduce the risk of serious illness.