Activation of blood neutrophils in horses with the use of different doses of endotoxin

The aim of the study was to determine the influence of various doses of lipopolysaccharides (LPS) on the phagocytic activity of neutrophils in 12 clinically healthy mares. Three mares were regarded as the controls; the experimental groups consisted of the remaining animals divided into 3 groups of 3 mares each. All experimental animals were treated with intravenous infusion at doses of 0.02, 0.05, and 0.2 μg LPS/kg b.w. Clinical examinations and blood collecting were performed directly before endotoxin injection and hourly for the first 8 h and 24, 48, 72, and 96 h thereafter. The results of clinical and haematological examinations of the experimental animals were typical for endotoxemic horses. The range of clinical value alterations was dependent on the LPS doses. An increase in the percentage of phagocytic cells, phagocytic indexes and NBT reduction was found in all experimental horses. The increases remained unchanged from a few to 96 h with respect to the doses used. The highest phagocytic activity of neutrophils was revealed in horses injected with a dose of 0.05 μg LPS/ kg b.w.