Age-related differences in the febrile response of the New Zealand White rabbit to endotoxin.

The effect of age on the febrile response of New Zealand White rabbits was investigated by administering bacterial endotoxin intravenously to animals from two different age groups. Rabbits greater than 2.0 years of age developed significantly smaller fevers than did animals that were less than 1.0 year old (p less than 0.001). The deficit in the febrile response of older animals was specifically related to an absence of the second peak of fever.