Pericardial Disease in Dogs

Overview of Canine Pericardial Disease

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.

Illness that Affect the Canine Pericardium

Several illnesses can affect the pericardium in dogs. 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

Signs of Pericardial Disease in Dogs may include:

• Weakness
• Collapse
• Difficulty breathing
• Pale gums
• Lack of appetite

Diagnosis of Pericardial Disease in Dogs

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 of Pericardial Disease in Dogs

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.

In-depth Information on Pericardial Disease in Dogs

There are a variety of causes of pericardial disease.

• Peritoneopericardial diaphragmatic hernia is a congenital disorder with no known cause. It is present from birth.
• Pericardial effusion often occurs secondary to pericarditis i.e. inflammation of the pericardium. Fluid that accumulates within the pericardium may be a result of either peritoneopericardial diaphragmatic hernia, right-sided heart failure, cysts, low blood protein, or infection. Bleeding into the pericardium may be caused by heart tumors, trauma, or blood clotting problems. In some cases, the cause of the pericardial effusion cannot be determined.
• Pericardial constriction most often develops secondary to chronic inflammation, particularly from infection, but also occurs secondary to recurrent hemorrhage or as a consequence of diffuse cancer.

Pericardial disease can occur in dogs of any age. Weimaraners are predisposed to peritoneopericardial diaphragmatic hernias. Golden retrievers are more likely to have bleeding in the pericardium from an unknown cause. Heart tumors, primarily hemangiosarcoma, are more common in German shepherds, golden retrievers and Labrador retrievers. Another type of heart tumor, called an aortic body tumor, is especially common in older short-nosed breeds such as pugs, bulldogs or Pekingese.

The prognosis for pericardial disease depends on the cause. Dogs with bleeding into the pericardium from an unknown cause have a fair to good prognosis. Dogs with pericardial fluid accumulation caused by infection have a guarded prognosis. Dogs with pericardial fluid accumulations arising as a result of a heart tumor have a poor prognosis.

Diagnosis In-depth of Pericardial Disease in Dogs

Various diagnostic tests are needed to diagnose pericardial disease and determine the underlying cause in dogs. Tests may include:

• A complete blood count (CBC) is performed to evaluate the red blood cells, white blood cells, and platelets. In some affected dogs, the red blood cell count may be low, indicating anemia. Elevation of the white blood cell count tends to indicate infection.
• Serum biochemical profile is performed to evaluate serum electrolyte levels and organ functions. Various abnormalities may be detected, including concomitant kidney disease or liver disease.
• Radiographs (X-rays) of the chest are helpful to help determine whether pericardial disease is present. When pericardial effusions are present, the heart is seen to be larger than normal and globoid in shape. If a hernia is present, loops of intestine may be seen overlying the heart.
• A barium series may be recommended if a peritoneopericardial hernia is suspected but cannot be confirmed on plain radiographs. Barium is a liquid that, when ingested, shows up readily on X-ray. If loops of intestine are present within the pericardium, barium highlights their presence.
• An ultrasound is the best way to diagnose pericardial disease. Ultrasound of the heart, called an echocardiogram, shows if whether a hernia or fluid is present. With the aid of ultrasound, fluid can be removed from around the heart by means of a needle and the fluid can be evaluated. In addition, the heart can also be assessed for evidence of a tumor.

Treatment In-depth of Pericardial Disease in Dogs

Treatment varies on the type and severity of pericardial disease. Treatments may include the following:

• For most cases of peritoneopericardial diaphragmatic hernia, no treatment is necessary since most dogs are clinically unaffected. If a dog with a hernia of this type becomes ill and has difficulty breathing, surgery must be performed to repair the hernia.
• The treatment for pericardial effusion involves removal of the fluid and treatment of the underlying cause. Once a significant amount of fluid is removed with a catheter or needle, additional therapy can be administered. Sometimes, repeated removal of fluid may be needed.
• Medical therapy for treatment of pericardial effusion is not commonly recommended. If an affected dog has collapsed with profoundly low blood pressure, intravenous fluids may be indicated for resuscitation. Furosemide or other medications designed to reduce fluid accumulation in the pericardium have not been shown to be effective.
• Surgery may be necessary for successful management of pericardial disease. Removal of the pericardial sac may be needed in recurrent hemorrhagic effusion of unknown cause, especially in younger dogs. The treatment for infective pericardial disease involves catheter drainage of the pericardium, subsequent surgical removal and drainage of the pericardial space (to prevent constriction), and specific antibiotic therapy based on culture.

Surgery is also indicated if constrictive pericardial disease is diagnosed or highly suspected. If a tumor is suspected but not confirmed on ultrasound, surgery may be needed to determine whether the tumor is present and, if present, to facilitate its removal. In some cases of hemorrhagic pericardial effusion caused by tumors, a small window may be cut into the pericardium to allow the blood to leak out of the sac and into the chest cavity, where it can be absorbed.

Follow-up Care of Dogs with Pericardial Disease

After treatment, affected dogs should be closely monitored for up to a year. Repeated X-rays and ultrasound should be performed at intervals to monitor the response to therapy and to check for recurrence/deterioration. Repeated blood work is recommended if initial results revealed abnormalities.

Dogs with pericardial disease can deteriorate rapidly. In particular, dogs with pericardial disease caused by tumors often succumb to the disease process shortly after diagnosis.