Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein of the lipocalin family. 1,12 It is produced by different tissues and exists in three different molecular forms: a homodimeric form synthesized as a component of late granules in activated neutrophils, a monomeric form secreted by injured kidney tubule epithelial cells, and a heterodimeric form in tubular cells that is rarely detected during kidney injury. 10 In dogs, urinary NGAL (uNGAL) elevations precede rises in creatinine and are shown to be an early renal biomarker of acute kidney injury (AKI) and chronic kidney disease (CKD). 11 In one study, using the AKI International Renal Interest Society (IRIS) grading system, uNGAL was found to be more sensitive than creatinine and could distinguish dogs at risk for or with IRIS grade 1 AKI from healthy dogs. 11 While mainly a biomarker of AKI, serum NGAL (sNGAL) expression in normal tissue acts as protection against bacterial infection. Therefore, systemic inflammation and infectious comorbidities cause upregulation of sNGAL expression. 12 Similarly, in horses, the sNGAL molecule has been demonstrated to increase following AKI, 7,14 but its concentrations are also affected by inflammatory processes in a comparable way to serum amyloid A (SAA) in a preliminary study. 14 Therefore, sNGAL holds potential to serve as a diagnostic tool for renal damage and inflammatory conditions in horses.