The aim of this study was to compare the effects of isotonic sodium chloride (ISS-0.9%), hypertonic sodium chloride (HSS-7.2%), HSS + lactate ringer solution (LRS) and HSS + sodium bicarbonate solution (SBS-1.3%) in the treatment of dogs with endotoxaemia. Endotoxaemia was induced by slow injection of a 1 mg/kg/i.v. dose of E. coli endotoxin (0111:B4). At the treatment stage, four groups, each composed of six dogs, were formed and a different treatment plan was carried out in each group: ISS, HSS, HSS + LRS and HSS + SBS. Clinical, haematological and biochemical examinations were performed before and after endotoxaemia. Hypotension (MAP < 60 mm Hg), leukopaenia and trombocytopaenia were observed during endotoxaemia in all dogs. MAP and plasma volume were increased in all groups except the ISS group. HCO-3 values were increased in the HSS + SBS group and decreased in the other groups. Therefore, it was concluded that the HSS + SBS combination was the most effective model of fluid therapy in the treatment of dogs with endotoxaemia.