Utility of neutrophil gelatinase-associated lipocalin in identifying septic cavitary effusions in dogs

Background Neutrophil gelatinase-associated lipocalin (NGAL) is an accurate marker of septic cavitary effusions in people. Hypothesis/Objectives To evaluate the utility of serum and effusion NGAL concentrations in differentiating septic effusions from effusions caused by other etiologies in dogs. Animals Fifty dogs with pleural or peritoneal effusion. Methods Ten dogs were prospectively enrolled into each of 5 groups based on effusion etiology: hypoalbuminemia, increased hydrostatic pressure, neoplastic, inflammatory, and septic. Concentrations of NGAL were measured in both serum and effusion. Results While median serum NGAL concentrations did not significantly differ between dogs with hypoalbuminemia (24.8 ng/mL, range 5.0–110.0 ng/mL), increased hydrostatic pressure (13.2 ng/mL, range 5.8–46.9 ng/mL), abdominal neoplasia (13.8 ng/mL, range 3.2–27.3 ng/mL), inflammatory (15.8 ng/mL, 5.6–36.6 ng/mL), or septic causes (19.2 ng/mL, range 7.2–64.8 ng/mL) of effusion (P = .272), median effusion NGAL concentrations were significantly higher in the septic group (194.4 ng/mL, range 120.0–1471.1ng/mL) than in the hypoalbuminemic (10.7 ng/mL, range 4.1–27.8 ng/mL, P < .001), hydrostatic (22.7 ng/mL, range 11.3–56.7 ng/mL, P < .001), neoplastic (65 ng/mL, range 15.7–215.3 ng/mL, P < .001), or inflammatory (45 ng/mL, range 33.8–195 ng/mL, P < .001) groups. Conclusions and clinical importance Concentrations of NGAL in effusions were significantly higher in septic effusions than in effusions of other etiologies. These findings suggest that effusion NGAL concentrations could be a helpful marker in the identification of cases with septic effusion.