Feline IL-17A (Interleukin-17A) is a pro-inflammatory cytokine belonging to the IL-17 family that plays an important role in host defense and inflammatory responses in cats (Felis catus). 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 inflammatory 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 enhancing mucosal and barrier immunity. In healthy cats, basal IL-17A expression is typically low, but levels may increase during bacterial or fungal infections, chronic inflammatory conditions, and certain immune-mediated diseases. Elevated IL-17A has been implicated in feline inflammatory bowel disease, chronic gingivostomatitis, asthma, dermatologic inflammation, and possibly tumor-associated inflammation. In veterinary and comparative medicine research, feline IL-17A serves as a biomarker of Th17-mediated immune activation and neutrophilic inflammation, providing insight into mucosal immunity, chronic inflammatory disease pathogenesis, and potential immunomodulatory therapeutic targets in feline health.