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TOday'S VeTerinary PracTice | September/October 2015 | tvpjournal.com TOday'S TecHnician Peer reviewed 70 the right atrial region or right atrial appendage » chemodectomas are often found at the heart base » Mesotheliomas and metastatic tumors may be identifed. • idiopathic pericardial effusions often are linked to inflammatory or immune processes. in these idiopathic cases, the effusion is sterile, and often hemorrhagic. Thickening of the epicardium and pericardium may be seen during histologic examination, along with associated inflammation. • infectious processes occur least commonly, but can include fungal disease, such as coccidiomycosis, and, rarely, bacterial pericarditis. congestive heart failure, uremia, and decreased oncotic pressure can result in small-volume pericardial effusion, usually without cardiac tamponade. 1 PRESENTATION Prevalence Pericardial effusion is commonly seen in golden retrievers and other medium to large breed dogs. any age dog can be affected, although one study noted the median age of dogs with idiopathic pericardial effusion was 7 years, while in dogs with nonidiopathic effusions, the median age was 9 years. 4 This same study found a higher prevalence of pericardial effusions in male dogs. Clinical Signs Patients experiencing chronic pericardial effusion may demonstrate weakness, abdominal enlargement, cough, tachypnea, and episodes of syncope. in those with acute pericardial effusion, acute episodes of collapse and weakness may be evident. 2 as pericardial fuid accumulates, shock and death can occur. Physical Examination Table 1 lists cardiac signs that may be noted upon physical examination of patients with pericardial effusion. The patient frequently has a decreased level of consciousness due to a decrease in oxygen delivery to the brain, 1 and patients with infectious pericarditis may be febrile. 2 TYPES OF FLUID While it is important to understand which types of pericardial effusion are more likely to be seen with certain conditions, cytology of pericardial effusions is rarely able to differentiate between neoplastic and idiopathic causes. The etiology of pericardial effusions is most commonly determined by echocardiography (see Management, page 72). Hemorrhagic effusions are common in dogs, while transudates are moderately frequent in dogs and cats. exudative effusions are fairly rare in small animals. Hemorrhagic Effusions Hemorrhagic effusions appear dark red, with a: • Packed cell volume > 7% • Specific gravity > 1.015 • Protein concentration > 3 g/dL. Hemorrhagic pericardial effusions in canine patients are commonly caused by hemangiosarcoma. Heart base tumors, pericardial mesotheliomas, malignant histiocytosis, lymphoma, and metastatic carcinomas may also cause hemorrhagic pericardial effusion. TABLe 1. Physical examination: cardiac signs of Pericardial effusion clinical siGn furtHer descriPtion Increased heart rate • Results from decreased cardiac output • Due to sympathetic nervous system activation Jugular distention Results from decreased output from right side of the heart, which causes a backup of blood into the cranial vena cava and jugular veins Muffed heart sounds Noted on auscultation Pale mucous membranes Result from vasoconstriction and decreased peripheral perfusion Poor pulse quality Due to lower stroke volumes and blood pressure Pulsus paradoxus • Decrease in systolic blood pressure (> 10 mm Hg) during inspiratory phase of breathing • Seen in instances of cardiac tamponade • Detected by palpating pulse pressure in a peripheral artery (ie, the femoral artery) Slower capillary refll time Results from decreased cardiac output Note: While pericardial effusion itself does not create a murmur, concurrent cardiac disease may result in one.