Pericardial Effusion in dogs

Fluid Around the Heart in Dogs: a Challenging Condition


There are several conditions that can affect our dog’s heart as they begin to age, or just because of their breed. One of the most common cardiac conditions is the appearance of fluid around the heart in dogs.

Fluid Around the Heart in Dogs – Pericardial Effusion

The cardiac condition where fluids build up around the heart inside the pericardial sac (pericardium) is called a pericardial effusion. It is normal for the pericardium to have a small amount of fluid in its sac for lubrication, making it easier for the heart to move within it.

An abnormal amount of fluid accumulation around the heart is interfering with its ability to pump blood.

Symptoms of Fluid Around the Heart

Symptoms of this condition vary depending on the speed of onset with which the condition is affecting the dog. This is when veterinarians will want to determine if the pericardial effusion is acute or chronic to decide what type of treatment is required.


Symptoms and clinical signs can range from fainting and collapse to exercise intolerance and an enlarged belly. The most common observation in veterinary hospitals of dogs that were later diagnosed with pericardial effusion was weakness, lethargy and collapse or fainting.

Fluid Around the Heart in Dogs

When symptoms are first noted, the dog should immediately be taken to the veterinarian for proper diagnosis. Treatment and care will vary significantly depending on the underlying cause.

Acute vs Chronic – What are the Symptoms

The symptoms that are noticed with an acute onset of pericardial effusion are typically fainting, collapse or worst-case scenario, death. Some owners confuse episodes of fainting with seizures due to stiffened or shaking limbs and confusion.

Chronic pericardial effusion will show symptoms slowly over time and may not be immediately noticed. Usually, owners report coughing, exercise intolerance, weight loss and distended abdomen.

How is Fluid Around the Heart in Dogs Building Up?

There can be several reasons that fluid accumulates within the pericardial sac.

Pericardial effusion can be caused by tumors that are growing within the heart or just on the pericardial sac. This condition can also be caused by inflammation which is usually secondary to an infection of the pericardium. In some cases, the cause of the inflammation is unknown, also referred to as idiopathic.

Pericardial Effusion in dogs

Causes such as trauma, congestive heart failure, breed and clotting factor abnormalities are also common reasons causing pericardial effusion.

Are There Certain Breeds That Are Prone to Fluid Build-Up Around the Heart?

There are several dog breeds that are more susceptible to this condition. It is typically due to overbreeding and poor genetic standards.

Fluid around the heart in dogs is common in the following breeds: Boxers, Bulldogs (French or English), Poodles, Boston Terriers, Golden Retrievers and Weimaraners. Any mixes with these breeds are also at higher risk.

How Is Fluid Around the Heart Diagnosed?

There is no single diagnostic method to confirm fluid build-up around the heart in your dog. Your veterinarian will use several ways to help them diagnose your dog with this cardiac condition. They include a physical exam, electrocardiography, radiography (x-rays), ultrasound (echocardiogram) and blood analysis.

Physical Exam

Performing a physical exam can be very helpful in diagnosing different health issues in our pets. Your veterinarian may find several things or just one that may lead him to suspect pericardial effusion. Their suspicions should always be backed up with further diagnostics.

Some physical exam findings of pericardial effusion can include muffled heart sounds, pale gums, abnormal pulses (pulsus paradoxus), fluid-filled abdomen, increased or abnormal respirations. Age and breed can also be an indicator of this condition.

The presence of a heart murmur is not always indicative of this condition however.

Electrocardiogram of a dog

 Electrocardiogram (ECG/EKG)

An electrocardiogram is a common tool used for diagnosing pericardial effusion. There are several distinct findings that can help understand if the assumed diagnosis is correct. A normal ECG does not necessarily mean there is no fluid build-up within the pericardium.

Ultrasound or Echocardiogram

An echocardiogram is a test that uses ultrasound to interpret conditions with the heart. This procedure is crucial in diagnosing the pericardial effusion as well as its severity. This tool is extremely important for identifying cardiac masses as well as interpreting the overall function and blood flow of the heart.

Ultrasound-guided Pericardiocentesis

In rare emergent cases of acute collapse and low cardiac output pericardiocentesis may need to be performed. This is where a veterinarian will take a syringe and needle and insert it into the chest cavity between the 5th and 6th rib space and withdraw fluid that is impending upon the heart.

When this is successful and positive results are seen, sending the fluid in for analysis would be warranted. Analysis of the fluid can be helpful in identifying if the underlying cause of the pericardial effusion was inflammatory or infectious.

Radiograph (x-rays)

When using radiographs to confirm that fluid around the heart in dogs is present, the first thing that is noted is an above normal heart size or cardiac silhouette. Sometimes the heart may also appear round or have a “sharp” edged appearance due to decreased heart motion.

Please note that radiographs are not a conclusive method to diagnose pericardial effusion but it can also provide an indication on how well the heart is actually functioning.

Physical Exam of a dog at the vet

Blood Analysis

Depending on the underlying cause of the fluid build-up around the heart, laboratory blood analysis may or may not be very telling. In most cases, an increase in kidney values can be seen due to a decrease in the heart’s functionality and the ability to circulate blood to other organs.

What Happens When a Dog Has Fluid Around the Heart?

When fluid accumulates within the pericardial sac, causing pericardial effusion, it leads to what is called cardiac tamponade. When the pressure in the pericardium becomes too high then the chambers of the heart cannot expand to fill with blood. At this point, the heart can no longer properly pump blood to the rest of the body.

How Do You Treat This Condition?

The first step to treating pericardial effusion in dogs is by identifying any underlying cause and going from there. Because there are several reasons that a dog may develop this condition, there are also several ways to treat it. Unfortunately, no treatment option seems to be simple and risky procedures may need to be performed in order to provide relief.


Sometimes performing a pericardiocentesis in order to remove some of the fluid from the pericardial sac is also necessary in order to correct the life-threatening cardiac tamponade condition.

This procedure should only be performed with ultrasound guidance because it involves sticking a needle dangerously close to the heart. It is important to know that it will not cure the condition and is potentially deadly if complications were to arise.

If your dog is not showing any signs of cardiac tamponade then pericardiocentesis should not be considered.

Symptoms Of Fluid Around the Heart

Surgical Treatment

Tumors or masses are common causes of fluid build-up around the heart in dogs. In some cases, surgical removal of the pericardial mass may be performed while others are treated with chemotherapy. Some owners opt for supportive care and oral diuretics instead of surgery or chemo.

Some specialists will recommend a surgical procedure called pericardectomy, which is where a piece of the pericardium is removed, allowing for the fluid to drain. In rare cases, this treatment is actually successful. Some doctors will only recommend it for temporary relief.

The Prognosis for Fluid Around the Heart In Dogs

The prognosis for this condition varies significantly depending on what the underlying cause is. In most cases that were unrelated to trauma, the life expectancy is less than two years after diagnosis of pericardial effusion.

Any pericardial effusion that is linked to cancer, is strictly dependent on the type of cancer you are dealing with. Many of these cases respond well to pericardiocentesis initially but relief is only temporary as symptoms and clinical signs usually remerge later.

Because many of these aortic or pericardial tumors tend to be slowly evolving, the prognosis is more positive than in the case of infectious pericarditis or hemangiosarcoma. Pericardial effusion in dogs is another condition that is dictated based on the severity of the heart disease.

Unfortunately, the prognosis for many cases of fluid around the heart in dogs is guarded. While this is better than poor, it is still a matter of quality of life in most scenarios.