2004). Fever does not generally occur in response to infection in infants less than 1 month; in fact, these neonates often have a hypothermic response to infection (Hofer et al. 2012). In our study, pyrogenic cytokines such as TNFα, IL‐1, and IFNy were upregulated in LPS‐treated pups, but one of the other powerful pyrogenic cytokines, IL‐6 was not. This evidence concerns the gene IL1A and infection.