Pleural effusion in the cat: a focus on laboratory diagnosis

Pleural eff usions constitute a common entity in feline medicine. Laboratory evaluation of
pleural fl uids remains the cornerstone of a proper diagnosis. Total nucleated cell count,
total protein concentration and haematocrit values are the most important indices,
which, along with cytological fi ndings, are used for the classifi cation of an eff usion (transudate, modifi ed transudate, exudate, haemorrhagic eff usion). Occasionally, the biochemical examination of eff usions is necessary in order to determine the presence of fl uid of a more specifi c aetiology (chyle, feline infectious peritonitis eff usions,
septic exudates), while microbiological examination remains a standard procedure in suspected septic eff usions. After having considered the obtained information, clinicians are usually able to understand the aetiology behind cavitary fl uid accumulation and thus make the best therapeutic decision for the cat patient