Wilks’ lambda test for drug × time interaction, p < 0.0001) of vitamin C, a major water-soluble vitamin in normalization the pro-inflammatory cytokines (IL-1β, Il-6, IFN-γ, and TNF-α) when used in combination with tulathromycin in lambs with pneumonic pasteurellosis. This evidence concerns the gene IFNG and pasteurellosis.