Neutrophil markers for inflammation in dogs and cats

Abstract

BACKGROUND: Neutrophil cell population data (CPD), including fluorescent light intensity (NE-SFL) and side scatter (NE-SSC), are promising inflammatory markers in human sepsis but remain unexplored in dogs and cats. OBJECTIVES: Determine the diagnostic utility of NE-SSC and NE-SFL for detecting systemic inflammation in dogs and cats. METHODS: Dogs and cats with archived CPD, blood films, and acute phase protein (APP) measurements were included. Increased C-reactive protein (CRP) in dogs and Serum Amyloid A (SAA) in cats were considered indicative of systemic inflammation. CPD was compared with APPs, white cell count (WCC), neutrophil count, band neutrophil count, and toxic change grade. Optimal cut-offs and associated sensitivities and specificities were calculated using ROC curve analysis. Correlations were assessed using Spearman's coefficient. RESULTS: NE-SFL and NE-SSC were significantly increased in dogs and cats with systemic inflammation. The area under the curve (AUC) of NE-SFL was higher than that of NE-SSC, WCC, and band neutrophil count in both dogs (0.82) and cats (0.77). The optimal NE-SFL cut-off for detecting systemic inflammation was > 41.7 ch in dogs (sensitivity 80%; specificity 66%) and > 37.4 ch in cats (sensitivity 75%; specificity 67%). NE-SFL was positively correlated with APPs, WCC, neutrophil count, and band neutrophil count in both species. NE-SSC was positively correlated with APPs in both species and, in dogs, also with WCC, neutrophil count, and band neutrophil count. CONCLUSION: CPD, particularly NE-SFL, is a promising marker of inflammation in dogs and cats and could be especially useful when APP quantification or blood smear examination are unavailable.