Canine, Feline, Ferret, and Mink Interleukin-11 (IL-11) is a highly conserved cytokine that is identical at the protein level among dogs (Canis lupus familiaris), cats (Felis catus), ferrets (Mustela putorius furo), and mink (Neovison vison), reflecting strong evolutionary conservation within Carnivora. IL-11 is a member of the IL-6 cytokine family—which includes IL-6, IL-11, IL-27, IL-31, leukemia inhibitory factor (LIF), oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), and cardiotrophin-like cytokine factor 1 (CLCF1)—and signals through a receptor complex composed of IL-11Rα and the shared gp130 subunit, activating JAK/STAT3 and MAPK pathways. Functionally, IL-11 plays roles in hematopoiesis (particularly megakaryocyte maturation and platelet production), mucosal protection, epithelial cell survival, and regulation of inflammatory responses. In these carnivore species, IL-11 is implicated in gastrointestinal inflammation, tissue repair, reproductive biology, and potentially tumor progression, where dysregulated IL-11/STAT3 signaling may contribute to fibrosis or neoplasia. Because dogs and cats serve as important spontaneous models for human cancer, inflammatory bowel disease, and regenerative medicine research, and ferrets and mink are widely used in respiratory viral and infectious disease models, the conserved nature of IL-11 across these species supports cross-species reagent development and comparative studies of cytokine signaling, tissue repair mechanisms, and translational therapeutic targeting of the IL-11/gp130 pathway.