Compared to a reference bottlenose dolphin without metabolic perturbations, the current study identified activated cytokine gene expression, including TGF-β, TNF-α, IFN-γ, IL-18, IL-13, IL-10, and IL-4 in the liver or spleen of a geriatric bottlenose dolphin with hyperinsulinemia. The gene discussed is TNF; the disease is hyperinsulinism.