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Pericardial Effusion in Dogs

What Is Pericardial Effusion in Dogs?

Pericardial effusion in dogs occurs when fluid accumulates in the space between the heart and the pericardium, a thin membrane enveloping the heart. Under normal circumstances, this space remains free of fluid, allowing the heart to beat unrestricted within its sac-like enclosure. However, when fluid gathers in this area, it exerts additional pressure on the heart, impeding the chambers’ ability to adequately fill with blood. Consequently, the heart struggles to pump a sufficient amount of blood throughout the body, a condition known as cardiac tamponade.

While pericardial effusion is not a common occurrence in most dogs, its onset constitutes a medical emergency.

Symptoms and Types

Dogs afflicted with pericardial effusion typically exhibit severe illness, yet discerning pet parents may find it challenging to pinpoint pericardial effusion as the underlying cause. Symptoms may include:

  • Episodes of collapse or weakness
  • Lethargy or diminished tolerance for exercise
  • Loss of appetite or disinterest in food
  • Rapid or labored breathing
  • Gagging or instances of vomiting
  • Paleness in the gums
  • Abdomen distended with fluid

While these manifestations are indicative, they are not exclusive to pericardial effusion and could signal other emergent conditions. Should you observe your dog experiencing collapse, weakness, pallor, or alterations in mental state, it warrants immediate attention. Contact your veterinarian without delay.


Pericardial effusion in dogs can stem from various factors, including:

  • Tumors like hemangiosarcoma or heart base tumors
  • Idiopathic pericarditis, which denotes inflammation of the pericardium without a discernible cause
  • Clotting disorders
  • Heart failure
  • Exposure to toxins such as rodenticides (rat poison)
  • Low levels of blood protein
  • Infections

Among the potential causes, tumors of the heart and idiopathic pericarditis are the most frequently encountered culprits behind pericardial effusion.

While infectious origins of pericardial effusion are rare, they may result from penetrating foreign objects, typically sharp items that breach the body and potentially puncture the pericardium. Two bacteria, Actinomyces and Nocardia, have been associated with bacterial pericardial effusion. Additionally, the soil fungus Coccidioides immitis has been linked to cases of pericardial effusion.

Certain dog breeds may exhibit a predisposition to one or more causes of pericardial effusion. These breeds include Golden Retrievers, Labrador Retrievers, German Shepherds, Great Danes, Saint Bernards, Boxers, French Bulldogs, English Bulldogs, and American Bulldogs.


During the physical examination, veterinarians may detect muffled heart sounds, attributable to the fluid within the pericardial sac dampening the heart’s beats. They may also observe an elevated heart rate (tachycardia), indicative of the body’s attempt to compensate for reduced blood output. Changes in pulse characteristics, discerned by palpating the dog’s femoral artery or jugular vein, may also be noted.

Confirmation of pericardial effusion typically involves an echocardiogram (ultrasound of the heart), which reveals the presence of fluid in the pericardial sac. During the echocardiogram, veterinarians assess for additional cardiac abnormalities, such as enlarged heart chambers or cardiac tumors.

Pericardiocentesis, the insertion of a needle into the pericardial space to extract fluid, allows veterinarians to analyze the fluid’s composition—whether blood, plasma, pus, or chyle (lymphatic fluid and fats). Sedation is necessary for dogs undergoing this procedure to prevent movement.

Additional diagnostic measures to determine the underlying cause may include chest X-rays, abdominal ultrasonography, and standard blood and urine tests. Electrocardiography (ECG) may be utilized to evaluate the dog’s heart rhythm, while coagulation profiles may be conducted if there are suspicions of a clotting disorder or toxin exposure.


In cases where a dog has collapsed, emergency measures typically include administering oxygen and providing intravenous (IV) fluids to support circulation.

Short-term management of pericardial effusion causing cardiac tamponade often necessitates pericardiocentesis, which involves draining fluid from the pericardium. However, exceptions exist for dogs with coagulation disorders, ruptured heart chambers, or active hemorrhage. Removing fluid alleviates pressure on the heart, allowing it to function properly.

Long-term treatment focuses on addressing the underlying cause of pericardial effusion. In some instances, pericardiocentesis may need to be repeated as required.

For cases involving heart base tumors, specialized procedures like pericardial window creation may be performed to enable fluid drainage into the chest cavity for reabsorption. Recurrent idiopathic pericarditis may necessitate subtotal pericardiectomy, a surgical removal of the pericardium, typically conducted at referral hospitals.

Certain cancers associated with pericardial effusion, such as hemangiosarcoma, may require intervention from veterinary oncologists for chemotherapy to improve quality and length of life.

In the presence of infection, veterinarians may obtain culture samples to identify appropriate antibiotics. Preferred antibiotic classes include sulfonamides, aminoglycosides, penicillin derivatives, and select cephalosporins. Combination medications like amoxicillin-clavulanate may also be prescribed.

Dogs with heart disease leading to congestive heart failure may benefit from medications such as furosemide. Anticoagulant rodenticide toxicity cases necessitate administration of vitamin K1 to prevent bleeding, with severe bleeding potentially requiring a blood transfusion.

Recovery and Management

The prognosis for dogs with pericardial effusion is generally uncertain. If the fluid extracted from the pericardial sac is blood, the condition tends to be more severe compared to clear or blood-tinged fluid.

Hemangiosarcoma, an aggressive cancer, ranks among the primary causes of pericardial effusion, with survival typically ranging from weeks to months even with intensive treatment. Pet owners should be aware that this cancer often remains unnoticed until it presents noticeable symptoms.

In some instances, pericardial effusion may recur, particularly with conditions like idiopathic pericarditis or heart failure. Regular veterinary checkups are crucial, and pet owners should familiarize themselves with potential signs to detect a recurrence early on.

Pericardial Effusion in Dogs FAQs

What is the primary cause of pericardial effusion in dogs?

Cancer stands as the leading cause of pericardial effusion in dogs, with studies indicating that 71% of patients with pericardial effusion are affected by cancer. Hemangiosarcoma ranks as the most prevalent cancer responsible for pericardial effusion in dogs.

Is pericardial effusion in dogs a critical medical condition?

Pericardial effusion in dogs is indeed a critical medical condition and typically constitutes an emergency. If your dog exhibits symptoms of pericardial effusion, prompt veterinary attention is imperative.

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