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Pericardial effusions may be idiopathic, neoplastic, infectious, traumatic, toxic or may result from atrial rupture in dogs with myxomatous mitral valve disease (MMVD).
Pericardial effusions may be idiopathic, neoplastic, infectious, traumatic, toxic or may result from atrial rupture in dogs with myxomatous mitral valve disease (MMVD).
Neoplasia affecting the heart, heart base or pericardium is the most common cause of pericardial effusion in dogs.
'''Neoplasia''' affecting the heart, heart base or pericardium is the '''most common''' cause of pericardial effusion in dogs.
Idiopathic pericardial effusions are the second most common cause of pericardial effusion in the dog. Effusions are usually haemorrhagic and the cause is unknown. One study has demonstrated progression of idiopathic pericardial effusion to mesothelioma over time in a series of Golden Retrievers.
'''Idiopathic''' pericardial effusions are the second most common cause of pericardial effusion in the dog. Effusions are usually '''haemorrhagic''' and the cause is unknown. One study has demonstrated progression of idiopathic pericardial effusion to mesothelioma over time in a series of Golden Retrievers.
In cats, the majority of pericardial effusions are secondary to congestive heart failure. However, cardiac lymphoma, heart based tumours and a variety of metastatic tumours have been reported as causes of pericardial effusion.
Bacterial pericardial effusions have been reported, usually associated with penetrating wounds and migrating foreign bodies.
Coagulopathies, such as those resulting from rodenticide toxicity, can manifest as haemorrhagic pericardial effusion.
Hypoproteinaemia can cause pericardial effusion in both the dog and cat.
In cats, the majority of pericardial effusions are secondary to congestive heart failure caused by cardiomyopathy. However, cardiac lymphoma, heart based tumours and a variety of metastatic tumours have been reported as causes of pericardial effusion. Additionally, feline infectious peritonitis virus (FIP) may cause pericardial effusions.
===Signalment===
===Signalment===
Idiopathic pericardial effusion is most common in middle-aged, male, large and giant breed dogs. Golden Retrievers, Labrador Retrievers, Great Danes, Newfoundlands and St. Bernards are overrepresented.
Idiopathic pericardial effusion is most common in middle-aged, male, large and giant breed dogs. Golden Retrievers, Labrador Retrievers, Great Danes, Newfoundlands and St. Bernards are overrepresented.
====History & Clinical Signs====
====History & Clinical Signs====
Signs are vague and the diagnosis is easily missed. It is important to rule out pericardial disease in any animal presenting with exercise intolerance, collapse or ascites. Animals with low volume effusions, or those that are accumulating slowly may have no clinical signs.
Clinical signs include:
- Inappetence
- Lethargy
- Exercise intolerance
- Weakness
- Collapse
- Dyspnoea
- Weight loss
- Abdominal enlargement
====Physical Exam====
====Physical Exam====
-Muffled Heart Sounds
- Muffled heart sounds
- Right-sided congestive heart failure: jugular venous distension, jugular pulses, ascites, pleural effusion
-Decreased Respiratory Sounds
- Weak pulses due to poor cardiac output
- Pulsus paradoxicus (pulse quality varies excessively with respiration)
-Tachycardia
- Sinus tachycardia, compensatory mechanism for reduced cardiac output in order to maintain systemic blood pressure
====Radiography====
====Radiography====
====Electrocardiography (ECG)====
====Electrocardiography (ECG)====
- '''Electrical alternans''': variation in height of the QRS complexes, due to the heart swinging within the pericardial fluid
====Echocardiography====
====Echocardiography====
Pericardial effusion is visible as a hypoechoic (black) area surrounding the heart. Cardiac tamponade is characterized by collapse of the right atrium +/- the right ventricle during diastole or systole. In severe cases, there is also underfilling of the left ventricle which gives it the appearance of being thickened ('''pseudohypertrophy''').
-Right-side heart collapse during diastole (cardiac tamponade)
Echocardiography is also useful to establish the cause of the pericardial effusion. Mass lesions may be small and difficult to distinguish in some cases, but may be very easily identified in others. Haemangiosarcomas can be seen infiltrating the right atrium, whereas heart base tumours typically surround the aorta and pulmonary artery.
===Treatment===
===Treatment===