Ferret IL-17A (Interleukin-17A) is a pro-inflammatory cytokine belonging to the IL-17 family that plays a key role in host defense and inflammatory responses in ferrets (Mustela putorius furo). IL-17A is produced primarily by Th17 cells, as well as by γδ T cells and other innate lymphoid populations, in response to microbial infection and immune stimulation. It acts on epithelial, endothelial, and stromal cells to induce expression of pro-inflammatory cytokines, chemokines (such as CXCL8), and antimicrobial peptides, thereby promoting neutrophil recruitment and strengthening mucosal barrier immunity, particularly in the respiratory and gastrointestinal tracts. In healthy ferrets, basal IL-17A expression is typically low, but levels increase during bacterial or fungal infection, viral challenge, and inflammatory stimulation. In biomedical and translational research, ferret IL-17A is of particular interest in respiratory disease models—including influenza and SARS-CoV-2—where Th17-mediated responses contribute to neutrophilic inflammation and disease severity. Characterization of IL-17A in ferrets provides valuable insight into mucosal immune regulation, host–pathogen interactions, and the balance between protective immunity and immunopathology in a widely used model of human respiratory disease.