Pericardial disease is a frequently overlooked condition in veterinary medicine. It includes a range of disorders affecting the pericardium, the double-walled sac that surrounds the heart. One of the most significant concerns is pericardial effusion-a condition that can impact both pets and the veterinarians who care for them. This article reviews pericardial effusion, including its causes, diagnosis, treatment options, and prognosis, based on the latest veterinary research.
The pericardium serves several essential roles in supporting heart function. It protects the heart from infection, provides a frictionless environment for the heart to move during contractions, and helps maintain the heart’s position within the chest.
Pericardial effusion occurs when excess fluid accumulates in the pericardial sac, the membrane that surrounds the heart. The fluid can range from clear (transudate) to bloody or inflammatory (exudate). In severe cases, this buildup can lead to cardiac tamponade-a life-threatening condition where pressure from the fluid prevents the heart from filling properly, reducing cardiac output and potentially causing circulatory collapse.
Congenital pericardial disease (such as pericardial defects or absence) is rare. Acquired causes are far more common:
In both cats and dogs, common causes of pericardial effusions include:
The pericardium can stretch to accommodate small amounts of fluid, but as the volume increases, its elasticity is exceeded, leading to cardiac tamponade. This causes:
Animals with pericardial effusion often present with vague, heart-related symptoms such as exercise intolerance, lethargy, weakness, and sometimes fainting (syncope). In acute cases, sudden weakness or collapse may occur.
A good physical examination is the beginning of your investigations into potential pericardial effusion. You might record general signs of cardiac distress, such as:
Veterinarians should also be on the lookout for the following classic clinical signs of pericardial effusion and cardiac tamponade:
After the clinical exam, diagnostic tests are required. The following are most useful in diagnosing pericardial effusions in pets:
Echocardiography remains the ‘gold standard’ diagnostic test in pericardial effusions. Early/small effusions are first seen at the posterobasal left ventricle, but often these cases aren’t scanned until the effusion is all around the heart, at which point the heart appears to be suspended in a sonolucent void. The echo-free space can be measured during diastole in order to grade the effusion as small, moderate, or large.
Though less sensitive, chest X-rays can provide initial insights into heart size and shape as well as rule out other causes of coughing. Standard lateral and ventrodorsal views reveal a generally enlarged heart shape, which may be rounder than usual.
Electrocardiography (ECG) may reveal sinus tachycardia (and, less commonly, atrial and ventricular tachycardias), electrical alternans, and small QRS complexes.
Management strategies depend on the severity of the effusion and the underlying cause, but prompt treatment is always necessary. Instead of going into detail about treating pericardial effusions here, we’ve put together a webinar by Chris Linney MRCVS, an RCVS specialist in Veterinary Cardiology. You can access it here: Free Veterinary Cardiology Webinar:https://subscriptions.improveinternational.com/us-cardiology-content-subscription)
Understanding pericardial effusions in veterinary medicine is crucial for early diagnosis and effective treatment. Recognizing the signs and using appropriate diagnostic tools can improve outcomes for affected pets. If you need any advice about our veterinary cardiology CE options or help reflecting on your veterinary CE, head to our Content Hub.
Cardiology | Postgraduate Certificate and ISVPS General Practitioner Certificate | Online | Start date: May 2025
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