Canine Interleukin-16 (IL-16) is a proinflammatory cytokine that plays an important role in regulating immune cell recruitment and activation in dogs (Canis lupus familiaris). IL-16 is produced by several cell types, including CD8⁺ T cells, mast cells, eosinophils, and epithelial cells, in response to immune stimulation or inflammatory signals. Canine IL-16 functions primarily as a chemoattractant for CD4⁺ immune cells by binding to the CD4 receptor, promoting migration and activation of T helper cells, monocytes, and dendritic cells to sites of infection or inflammation. Through these actions, IL-16 contributes to coordination of immune responses and modulation of inflammatory signaling pathways. In dogs, IL-16 participates in immune responses against bacterial, viral, and parasitic infections and may influence inflammatory processes associated with allergic and autoimmune diseases. In cell culture, recombinant canine IL-16 is commonly used to study chemotaxis of CD4⁺ immune cells, investigate mechanisms of immune cell recruitment and activation, and evaluate cytokine-mediated regulation of inflammatory pathways. Due to these functions, canine IL-16 is studied in veterinary immunology and translational research, including investigations of immune-mediated diseases, allergy, and comparative inflammatory mechanisms relevant to both canine and human health.