Pericardial effusion is when fluid accumulates in the pericardium of the dog. The pericardium is a double-walled sac where the heart and the roots of the great vessels are found. The fluid can be serous or serosanguinous, i.e. clear/yellow fluid or bloody fluid. Pericardial effusion is not a disease in its self; it is instead a symptom that can be caused by a wide range of health problems.

Serous accumulation in a dog can be brough on by problems such as pericardial cysts, peritoneopericardial diaphragmatic hernias, hypoalbuminemia, uremia, or heart failure. Serosanguinous build up can be caused by rupture of the left atrial, clotting disorders, cancer, idiopathic disase, or trauma. Pericardial effusion in dogs can also consist of pus that has been produced as the result of an infection, but this is quite rare.

Which dogs get pericardial effusion?

Compared to other acquired cardiovascular problems in dogs, pericardial effusion is an uncommon condition for dogs. Some dog breeds are however more susceptible to pericardial effusion than other, such as Golden Retrivers, Great Pyrenees and Great Danes. A majority of the dogs that develop pericardial effusion are large or giant breed dogs, and they are typically male and of middle-age.

The result of pericardial effusion in dogs

When fluid starts to build up in the pericardial sac of your dog, it will increase the pressure within the sack and compress the chambers of the heart. The increasing intrapericardial pressure will first equilibrates with right-sided diastolic pressures, since the right atrial diastolic and right ventricular pressures are lower than the pressure in the left chambers of the heart. The increasing intrapericardial pressure will hence lead to a condition known as cardiac tamponade. When chambers on the right side of the heart of your dog gets compressed, the venous return will drop dramatically and cause jugular venous distention and ascites. The blood flow to the lungs will also be reduced, which leads to hypoxia and tachypnea.

What causes pericardial effusion in dogs?

As mentioned above, a wide range of health problems can lead to pericardial effusion in a dog. One of the most common reasons behind pericardial effusion in dogs is cardiac neoplasia, i.e. abnormal and uncontrolled cell growth in the heart. The second most common reason behind pericardial effusion in dogs is heart base tumours, especially chemodectoma or ectopic thyroid carcinoma.

Pericardial effusion treatment for dogs

A dog with pericardial effusion needs prompts treatment. In most cases, the vet will have to drain the sac to reduce pressure. A catheter can be placed through the right chest wall of the dog into the sac. As much fluid as possible should be drained from the sac, and a sample should preferably be sent to a laboratory for analysis. 

Diuretics should be avoided since they will reduce the blood volume, thereby causing the cardiac chambers to collapse even more. Broad-spectrum antibiotics are often administered to dogs with pericardial effusions. Corticosteroids are often given to horses with pericardial effusion, but no benefits for dogs have been scientifically shown.

Cardiovascular and circulatory problems in dogs: (click for more info)
Aortic stenosis in dogs
Congestive heart failure in dogs
Degenerative mitral valve disease in dogs
Dilated cardiomyopathy in dogs
Heart valve dysplasia in dogs
Hemolytic anemia in dogs
Patent ductus arteriosus in dogs
Pericardial effusion in dogs
Pulmonary hypertension in dogs
Pulmonic stenosis in dogs
Thrombocytopenia in dogs
Ventricular septal defect in dogs
Atrial septal defect in dogs
Tetralogy of Fallot in dogs
Von Willebrand disease in dogs