Fever response of sheep in the peripartum period to gram-negative and gram-positive pyrogens.

We have measured body temperatures and serum iron concentrations of sheep in the peripartum period following administration of endotoxin and Staphylococcus aureus cell walls. Both the rise in rectal temperature and the fall in serum iron concentration following intravenous injection of S. aureus were the same immediately pre- and postpartum as they were 5 weeks after parturition. The rise in rectal temperature following intravenous endotoxin injection immediately pre- and postpartum was significantly less than that of the same ewes 5 weeks later. However, the fall in serum iron concentration following endotoxin injection was significantly suppressed only prepartum. We conclude that fever is not suppressed in sheep in the peripartum period, but the response to endotoxin is suppressed, through complex processes incidental to the mechanism responsible for the maintenance of gestation and induction of labour.