New research published in the American Journal of Physiology Regulatory, Integrative and Comparative Physiology shows that bacterial infections increase the production of nitric oxide in chicks, which is similar to what happens in rodents. The increase in nitric oxide is thought to be related to the development of fever. In fact, when nitric oxide production was blocked, thermogenesis was inhibited and infected chicks began to huddle more to increase body temperature.
Dantonio V, Batalhão ME, Fernandes MHMR, Komegae EN, Buqui GA, Lopes NP, Gargaglioni LH, Carnio EC, Steiner AA, Bícego KC. Nitric oxide and fever: immune-to-brain signaling vs. thermogenesis in chicks. American Journal of Physiology Regulatory, Integrative and Comparative Physiology310: R896–R905, 2016.