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Fluid Buildup in the Sac Surrounding the Heart in Dogs

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Pericardial Effusion in Dogs


Pericardial effusion is a condition in which an abnormally large amount of fluid collects in the pericardial sac that surrounds the dog's heart (pericardium). A secondary condition, referred to as cardiac tamponade, results from this retention of fluid, as the swelling of fluid applies pressure on the beating heart, compressing it and restricting its ability to pump blood.


The pressure inside the heart increases, and since the right atrium and ventricles normally have the lowest cardiac filling pressures, they are the most affected by cardiac tamponade. With the pressure elevated inside the heart, the heart has a lower cardiac output, leading to right-sided congestive heart failure. Fluid retention throughout the body typically follows ascites, swelling of the limbs, and weakness or collapse.


Dogs and cats are both susceptible to pericardial effusion. If you would like to learn more about it affects cats, please visit this page in the PetMD health library.


Symptoms and Types


  • Lethargy
  • Vomiting
  • Anorexia
  • Pale gums
  • Abdominal distention
  • Exercise intolerance
  • Fainting or collapse
  • Respiratory distress
  • Increased breathing rate and/or increased heart beat rate




  • Congenital disorders (birth defects, or genetic traits)
  • Congestive heart failure (failure due to excess fluid retention)
  • Coagulopathy: a disease that affects the body's ability to clot (coagulate) blood
  • Constrictive pericarditis with fibrosis (inflammation of the pericardium with excess fibrous tissue)
  • Infection of the pericardium
  • Foreign object in the body causing internal distress
  • Left atrial tear or cardiac trauma
  • Cancer




Your veterinarian will perform a complete physical exam on your dog, including a blood chemical profile, a complete blood count, a urinalysis, and an electrolyte panel, in order to rule out underlying systemic diseases like cancer or infection. You will need to give a thorough history of your dog's health, onset of symptoms, and possible incidents that might have precipitated this condition.


Blood tests can help to diagnose disorder that has caused fluid buildup in the pericardial sac. If infection or cancer is the cause of the pericardial effusion, a pericardial fluid analysis can be done to identify the origin of the cancer, or the type of infection. Radiograph and echocardiograph imaging are crucial for correct diagnosis of pericardial effusion. An echocardiograph is even more sensitive than a radiograph for diagnosis of pericardial effusion. An electrocardiogram, which measures the electrical conductance of the heart, sometimes shows a distinct pattern if the animal is suffering from cardiac tamponade.




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