Background: Fluid resuscitation is widely considered a life saving intervention in septic shock however recent evidence has questioned both its safety and efficacy in sepsis. This study sought to compare fluid resuscitation with vasopressors with vasopressors alone in a hyperdynamic model of ovine endotoxemia. Methods: Endotoxemic shock was induced in sixteen sheep after which they received fluid resuscitation with 40mls/kg of 0.9% saline or commenced haemodynamic support with protocolized noradrenaline and vasopressin. Microdialysis catheters were inserted into the arterial circulation, heart, brain, kidney and liver to monitor local metabolism. Blood samples were recovered to measure serum inflammatory cytokines, creatinine, troponin, ANP, BNP and hyaluronan. All animals were monitored and supported for 12 hours after fluid resuscitation. Results: After resuscitation animals receiving fluid resuscitation required significantly more noradrenaline to maintain the same mean arterial pressure in the subsequent 12 hours (68.9mg vs. 39.6mg p=0.04). Serum cytokines were similar between groups. Atrial natriuretic peptide increased significantly after fluid resuscitation compared to animals managed without fluid resuscitation (335ng/mL (256-382) vs. 233ng/mL (144 – 292) p 0.04). Cross-sectional time series analysis showed the rate of increase of the glycocalcyx glycosaminoglycan hyaluronan was greater in the fluid resuscitated group over the course of the study (p=0.02) Conclusion: Fluid resuscitation resulted in a paradoxical increase in vasopressor requirement. Additionally, It did not result in improvements in any of the measured microcirculatory or organ specific markers measured. The increase in vasopressor requirement seen may have been due to endothelial/glycocalyx damage secondary to ANP mediated glycocalyx shedding.