Fever responses in newborn lambs.

Neonatal lambs failed to respond with an increase in body temperature to i.v. injection of both endotoxin (0.4 microgram/kg), a Gram-negative bacterial pyrogen, and the cell walls of Staphylococcus aureus (1 x 10(9), a Gram-positive bacterial pyrogen. However, the fall in serum iron concentration that normally accompanies injection of both the pyrogens in adults was not attenuated in the neonates. We believe that the central nervous system origin of the fever pathway is suppressed in neonatal lambs.