TABLE 30-5.
Guidelines for Categorization of Feline Pleural Effusions
| Translucent Effusions |
Opaque Effusions |
|||||
|---|---|---|---|---|---|---|
| Transudate | Modified Transudate | Nonseptic Exudate | Septic exudate | Chylous Effusion | Hemorrhage | |
| Color | Colorless to pale yellow | Yellow or pink | Yellow or pink | Yellow or pink | Milky white | Red |
| Turbidity | Clear | Clear to cloudy | Clear to cloudy | Cloudy to opaque; flocculent | Opaque | Opaque |
| Protein (g/L) | <25 | 25-50 | 30-60 (FIP: 35-85) | 30-70 | 25-60 | >30 |
| Fibrin | Absent | Absent | Present | Present | Variable | Present |
| Triglyceride | Absent | Absent | Absent | Absent | Present | Absent |
| Bacteria | Absent | Absent | Absent | Present | Absent | Absent |
| Nucleated cells/UL | <1000 | 1000-7,000 (LSA: 1000-100,000) | 5000-20,000 (LSA: 5,000-100,000) | 7000-300,000 | 1000-20,000 | Similar to that of peripheral blood |
| Cytologic features | Mostly mesothelial cells | Mostly macrophages and mesothelial cells; few nondegenerative neutrophils; may be neoplastic cells (LSA, carcinoma) in some cases | Mostly nondegenerate neutrophils and macrophages; neoplastic cells (LSA, carcinoma) in some cases | Mostly degenerate neutrophils, bacteria, also macrophages | Small lymphocytes, neutrophils, and macrophages in variable proportions | Mostly erythrocytes; macrophages with erythrocytosis |
| Disease associations | Hypoalbuminemia (glomerulopathy, hepatopathy, protein-losing enteropathy); early CHF (rare); hyperthyroid has been reported | CHF; neoplasia (LSA, carcinoma); diaphragmatic hernia | FIP; neoplasia; diaphragmatic hernia; lung lobe torsion; pancreatitis | Pyothorax | Chylothorax; obstructed thoracic duct or cranial vena cava (lymphangectasia, central venous thrombosis); ruptured thoracic duct, CHF, heartworm, neoplasia, idiopathic | Hemothorax Trauma Coagulopathies Lung lobe Torsion Neoplasia |
| Further diagnostics to differentiate causes | Blood biochemistry (perhaps T4), urinalysis with UPC; If primary hepatic: abdominal U/S and FNA, or fuller hepatic biopsy. If primary cardiac, echocardiography | Echocardiography NB hernia may not be seen on radiographs |
May need biopsy sample to differentiate neoplasia and FIP (although signalment often helpful); FIP: unresponsive pyrexia, hyperglobulinemia, nonregen erative anemia, lymphopenia (perhaps serology), coronavirus IFA of effusion fluid may help diagnose; neoplasia: LSA may be noted from cytology; pancreatitis may require laparotomy and biopsy | Culture and sensitivity required for appropriate antibiosis | Echocardiography; neoplasia may require FNA or biopsy; idiopathic by rule outs | Must distinguish between blood contamination of effusion; haemothorax fluid as haematocrit of 25-50% of that of peripheral blood History, presentation (mainly for trauma, exposure to rodenticides) Clotting factors. Neoplasia by U/S and FNA or biopsy (clotting factors first!) |
FIP, Feline infectious peritonitis; LSA, lymphosarcoma; CHF, congestive heart failure; U/S, ultrasound; UPC, urine protein:creatinine ratio; FNA, fine-needle aspirate; IFA, immunofluorescent assay; NB, nota bene.
Repeat radiography after pleurocentesis of effusion is often helpful diagnostically.