A novel equine P-selectin glycoprotein ligand-1 (ePSGL-1) is disclosed having the amino acid sequence set forth in SEQ ID NO:2. DNA sequences encoding the ePSGL-1 are also disclosed, along with vectors, host cells, and methods of making the ePSGL-1. The invention further provides methods for preventing or reducing acute inflammatory response in an equine subject by administering ePSGL-1 and fragments thereof (e.g., an ePSGL-1-Ig fusion protein). The invention also provides methods for identifying compounds capable of reducing or preventing damage to tissue or organs caused by acute inflammatory response in an equine subject.