The effects of corticosteroid administration on the migration, phagocytosis and bactericidal capacity of equine neutrophils

Neutrophil function was evaluated in six clinically normal adult horses, immediately before and 3-6 hours after they were given one dose of hydrocortisone sodium succinate (1 mg/kg body weight). Random migration, stimulated migration to zymosan-activated serum, bacterial phagocytosis and bactericidal capacity of neutrophils were determined in vitro. The mean indices of stimulated migration (net migration and migration ratio) were significantly greater after CS administration (net migration = 62 +/- 23 micron; migration ratio = 11.5 +/- 6.7) than before CS administration (net migration = 44 +/- 10 micron; migration ratio = 6.0 +/- 3.1; P less than 0.05). Random migration, bacterial phagocytosis and bactericidal capacity of neutrophils were unchanged by CS therapy. Results from this study suggest that the migration of equine neutrophils is influenced, but not impaired, after one dose (1 mg/kg) of hydrocortisone sodium succinate and that the latter causes no change in the ability of equine neutrophils to phagocytize and kill Staphylococcus aureus.