Pleural Effusion (Fluid In The Chest) In Dogs: Symptoms, Causes, & Treatments

Schapendoe or Dutch sheepdog, Canis familiaris, resting in grass, tongue lolling. (Photo by: Auscape/UIG via Getty Images)

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Pleural effusion in dogs happens when there is a buildup of fluid in the area of the chest known as the pleural cavity, which is the sterile space surrounding the lungs and heart. When this occurs, it can put pressure on a dog’s lungs and make breathing difficult.

The condition can develop when the pleural cavity doesn’t absorb enough fluid or when too much fluid is being produced. Sometimes vets can find pleural effusion at regular checkups, but most often it isn’t found until dogs show symptoms of respiratory distress.

If you see the signs of pleural effusion in your dog, then you must consult your veterinarian for a proper diagnosis and treatment. Here’s what you should know about the symptoms, causes, and treatments for pleural effusion in dogs.

Symptoms Of Pleural Effusion In Dogs

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Symptoms of pleural effusion in dogs can start off mild when only a small amount of fluid accumulates in the chest, but they will get progressively worse as more fluid builds up. The condition, itself, can also be a symptom of other underlying issues.

If you see the following signs of pleural effusion in your dog, then get to your vet right away:

  • Exercise intolerance
  • Lethargy
  • Rapid or difficult breathing
  • Coughing
  • Excessive panting or breathing with mouth open
  • Anxiety, restlessness
  • Loss of appetite
  • Extending the neck, as if to get air
  • Taking unusual positions to breathe easier
  • Pale or bluish gums, tongue, or lips
  • Low body temperature
  • Shock

Causes Of Pleural Effusion In Dogs

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There are several types of pleural effusion in dogs, each with their own possible causes.

All of these types result in similar symptoms, though they may require different methods of treatment. Here are the types of pleural effusion in dogs and their causes:


This happens when there is an increase in hydrostatic pressure or decrease in oncotic pressure. Here are some possible causes:

  • Liver disease
  • Malnutrition
  • Malabsorption
  • Heart failure
  • Burns
  • Chronic hemorrhaging
  • Kidney disease
  • Intestinal disease


This happens when lymphatic fluid and chylomicrons accumulate. Here are a few possible causes:

  • Cancer
  • Chronic vomiting
  • Diaphragmatic hernia
  • Twisted lung lobe
  • Blood clot in the veins of the chest
  • Congenital defects present from birth


This happens when blood accumulates in the chest. Here are a few reasons that might occur:

  • Injury or trauma
  • Lymphoma
  • Tumors of the chest wall or heart


This happens when pus and fluid accumulates because of an infection or growth. Here are a few issues that might cause it:

  • Injury
  • Fungal or parasitic infection
  • Pancreatitis
  • Pulmonary thromboembolism
  • Heartworm
  • Pneumonia
  • Esophageal disease
  • Lupus
  • Rheumatoid arthritis

Treatments For Pleural Effusion In Dogs

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Immediate treatment for pleural effusion in dogs involves relieving respiratory distress through oxygen therapy and then draining fluid from the chest cavity with a needle and chest drain. These may need to be in place for several days depending on the severity of the condition.

Other tubes or shunts may be placed to draw fluid away from the chest cavity. Intravenous fluid may also be provided for dogs suffering from dehydration.

Further treatment often depends on the underlying cause of the fluid buildup. Cancer may be treated with chemotherapy or radiation, and infections may be treated with antibiotics. Sometimes exploratory surgery may be needed to determine the cause.

Dietary changes, exercise restrictions, medications, and follow-up vet visits may also be prescribed for recovering dogs.

The prognosis can vary a lot depending on the underlying cause.

Has your dog ever suffered from pleural effusion? How did your vet treat it? Let us know in the comments below!