Stimulation of airway neutrophils following dexamethasone administration and equid herpesvirus-2 challenge in horses.

The aim of this study was to investigate neutrophil stimulation following experimentally-induced airway inflammation in healthy horses. Six horses received dexamethasone and four were then inoculated with equid herpesvirus-2 (EHV-2). Significant neutrophilia was detected in tracheal wash and bronchoalveolar lavage fluid for up to 6days. Concentrations of neutrophil elastase (NE) and myeloperoxidase (MPO) were significantly increased compared to baseline for up to 14days in tracheal washes and both markers were significantly correlated with neutrophil counts. Serum levels of surfactant protein D were not significantly modified throughout the study. These results suggest that dexamethasone administration with or without EHV-2 inoculation is associated with a sustainable activation and degranulation of neutrophils in the trachea along with moderate modifications detectable in the lower airways.