Ovine Interleukin-13 (IL-13) is a Th2-associated cytokine produced primarily by activated CD4⁺ T helper 2 (Th2) cells and other type 2 immune populations in sheep (Ovis aries), where it plays a central role in regulating mucosal immunity, alternative macrophage activation, and tissue remodeling. IL-13 signals through receptor complexes composed of IL-13Rα1 and IL-4Rα, activating JAK/STAT6 pathways that promote IgE-associated responses, mucus production, suppression of certain pro-inflammatory cytokines, and support of wound healing and fibrotic processes. In ovine health, IL-13 is particularly important in immune responses to gastrointestinal nematodes and other parasitic infections, where Th2 polarization facilitates parasite expulsion and intestinal repair. IL-13 may also influence immune regulation in respiratory disease, mastitis, and chronic viral infections such as ovine progressive pneumonia (maedi-visna) by shaping the Th1/Th2 balance. While protective in limiting excessive inflammation and supporting tissue repair, prolonged or dysregulated IL-13 expression can contribute to fibrosis and chronic inflammatory pathology. As a biomarker of type 2 immune activation, ovine IL-13 is valuable in studies of host–parasite interactions, vaccine development, and genetic selection for disease resilience. Characterization of ovine IL-13 supports veterinary research into cytokine network regulation, mucosal immunity, and strategies to improve flock health and productivity.