Pericardial effusion is fluid in the sac (pericardium) that surrounds the heart. As the fluid accumulates it puts pressure on the heart and does not allow for normal function of the heart. If the heart cannot pump properly, the animal then goes into shock and death can occur. There are numerous causes for pericardial effusion such as neoplasia (cancer), idiopathic, infection, heart disease, clotting abnormalities, toxins and trauma. In dogs, the most common causes are neoplasia and idiopathic.
What does Pericardial Effusion look like in a Dog?
Dogs with pericardial effusion show clinical signs with the onset of cardiac tamponade. Cardiac tamponade is when compression occurs on the heart from the fluid accumulating. Dogs will often become lethargic, weak and not tolerate exercise. They can have collapsing episodes as well. If they have gone into heart failure from their pericardial effusion, fluid can accumulate in their abdomen giving a distended appearance. With the increased compression on the heart and decreased cardiac output, dogs will go into shock. Their blood pressure will drop, gums become pale in color, heart rates increase and they will collapse and die. Due to the severe nature of this disease process, rapid diagnosis and treatment is necessary.
Diagnosing Pericardial Effusion and The Cause:
There are several diagnostics that aid in diagnosing pericardial effusion and the possible causes. A thorough physical exam can show muffled heart sounds, weak pulses, pale gums, a fluid wave in the abdomen, and changes in breathing. Blood work can show clotting abnormalities, anemia or signs of infection. As mentioned above, if in shock the blood pressure in these dogs may be low. EKGs may show arrhythmias or electrical alternans, which is present from the swinging of the heart in the fluid as it beats. Radiographs of the chest will show an enlarged, globoid appearance of the heart. Ultrasound/echocardiogram of the heart will show the free fluid in the pericardium and possible masses associated with the heart or pericardium. More advanced imaging may be helpful as well.
Treating Pericardial Effusion:
Initial treatment involves sticking a needle into the pericardium (pericardiocentesis) to remove the fluid. This will aid in stabilizing the pet but is not curative. A pericardectomy or pericardial window surgery can be performed so that cardiac tamponade can no longer occur. If there is a mass/neoplasia, surgical removal may be necessary as well as chemotherapy. Prognosis is variable depending on the cause.
Author: Kerri Wiedmeyer, DVM, Emergency Veterinarian, Wisconsin Veterinary Referral Center