Effusion in the cat: classification of 396 fluids according to a problem-oriented scheme

An effusion is an abnormal accumulation of fluid within a body cavity (abdominal, thoracic, pericardial) and it is a common sign of several disorders in cats. Examination and classification of effusions can help to establish the cause of disease and to provide useful information for diagnosis and prognosis. The aim of this study was to classify feline effusions according to a problem-oriented approach in order to reduce the diagnostic differential. Three hundred and ninety-six thoracic and abdominal feline effusions were classified using both cytological criteria and refractometrical estimates of total protein concentration. This study revealed the high prevalence of lymphorrhagic effusions (23.2 %) and the rarity of bile peritonitis (0.3 %), mesothelial hyperplasia (0.5 %), and eosinophilic exudates (0.8 %) in the cat. Our problem-oriented classification scheme appears to be clinically useful, providing a reduced diagnostic differential, and drives the clinician to perform additional diagnostic tests.