Pericardial Effusion in Dogs

The pericardium is a thin membrane that surrounds the heart, protecting it from infection and lubricating the space it requires in the body cavity to pump effectively. This membrane typically contains 1 - 2 teaspoons of liquid. The pathological definition of effusion is when a fluid escapes from an area it typically occupies into another zone/area/space. Pericardial effusion is a condition in which excess fluid has accumulated in the pericardial sac around the heart. This excess fluid can impede the heart’s ability to properly fill with blood during the relaxing phase, leading to less blood being shuttled through with each cycle/beat.

Pericardial effusion is uncommon in dogs and symptoms can be slow to manifest as the heart can adjust for some time if it occurs gradually.

If the pressure in the pericardial sac causes an increase in the pressure inside the heart, it is an emergent condition known as cardiac tamponade. Cardiac tamponade is an emergency that leads to death if untreated, as the heart is unable to pump blood around the body effectively.

In cases where cardiac tamponade is not present prognosis is dependent on the primary condition causing pericardial effusion.

Some dogs are at higher risk of developing pericardial effusion including German Shepherds, Golden Retrievers, Boxers, Bulldogs, Boston Terriers, French Bulldogs, Afghan Hounds, Salukis, Weimaraners and Labrador Retrievers. This condition is also more commonly seen in male, middle aged, large breed dogs.

Pericardial effusion can also be idiopathic, meaning there is no known cause. The 2 most common causes of pericardial effusion are tumors and idiopathic pericardial effusion.

The cancer most commonly leading to pericardial effusion is hemangiosarcoma; an aggressive cancer leading to excessive blood accumulation in the pericardium. The second most common cardiac tumor in dogs is chemodectomas. Other possible cancerous causes include: (hemangiosarcoma, chemodectoma, lymphoma, mesothelioma).

Commonly, symptoms of pericardial effusion may not become apparent until disease is severe. Onset in senior animals may appear similar to typical “slowing down” with age, or be mistaken for weight gain due to abdominal swelling.

Common diagnostic procedures include;

• Blood tests (including clotting tests)
• Urinalysis
• Diagnostic imaging (x-rays, echocardiography)
• Physical examination
• Patient history
• Laboratory analysis of fluid from pericardiocentesis
• Heart rate monitoring/electrocardiography (ECG or EKG)

Initial treatment is commonly focused on stabilizing the dog as this condition is emergent. Subsequent treatment varies depending on the underlying disease that caused the fluid buildup. If the underlying cause is not addressed, pericardial effusion is likely to recur.

Treatment options include;

• Supplemental oxygen
• IV fluids
• Medications
• Decompression/aspiration/drainage of pericardium (pericardiocentesis)
• Surgical removal or disruption of the pericardial sac (pericardiectomy and percutaneous balloon pericardiotomy)
• Radiation and chemotherapy if cancer present

Referral to a specialist, such as a cardiologist, criticalist or internist, is recommended to find and treat the initial cause of fluid accumulation.

Pericardial effusion often presents as an acute emergency, although the effusion may have been accumulating slowly over time. As pericardial effusion is usually a secondary condition, treatment and prognosis is highly dependent on the root cause of the inflammation or fluid source. Hemangiosarcoma survival is measured in weeks or months, whereas half of idiopathic pericardial effusion cases are cured after a pericardiocentesis.

Commonly long-term outcomes are poor, as non-hemangiosarcoma associated cases are rare. Instances where the primary condition is non-cancerous, outcomes are more favorable as treatments are more effective.

There is no conclusive research on/indication of how to prevent pericardial effusion. Routine veterinary care and proper/consistent/effective treatment of heart cancerous conditions may lower the risk of developing pericardial effusion, but there is no conclusive way to prevent the condition.

Pericardial effusion is not contagious.

Pericardial effusion is uncommon in dogs.

Typical treatment includes;

• Supplemental oxygen
• IV fluids
• Medications
• Decompression/aspiration/drainage of pericardium (pericardiocentesis)
• Hospitalization
• Treatment of the underlying cause
• Surgical incision into the pericardium to reduce fluid buildup (pericardiectomy)