The effect of infection on gluconeogenesis was assessed in the chronically catheterized conscious dog. Dogs were studied 42 h after implantation of a sterile (n = 7) or an Escherichia coli containing (n = 7) fibrinogen clot into the peritoneum (54 h fasted). Infection increased arterial plasma glucagon and cortisol (4.2- and 2.1-fold, respectively), but it did not alter arterial plasma insulin, catecholamines, or glucose concentrations. Infection increased tracer ([3-3H]glucose) determined glucose production and utilization and net hepatic glucose output by 35%. Net hepatic alanine and lactate uptake were also increased by 34 and 54%, respectively, without an alteration in their net hepatic fractional extraction. The intrahepatic efficiency of conversion of [14C]alanine to [14C]glucose was not decreased in the septic dog (.77 +/- .08) vs. .95 +/- .10 in noninfected and infected, respectively). Intestinal glucose uptake and lactate release were increased approximately twofold. The increase in intestinal lactate release accounted for 35% of the increase in net hepatic lactate delivery seen in response to infection. In conclusion, a good model of hypermetabolic infection was developed in which the characteristic increases in hepatic glucose production and gluconeogenesis were observed in the fasted state. The increase in gluconeogenesis was due to an increase in hepatic gluconeogenic precursor uptake with no impairment in the net fractional hepatic extraction of gluconeogenic precursors or the efficiency of gluconeogenesis. In addition, the intestine is a significant contributor to the increase in gluconeogenic precursor supply seen in response to infection.