Background: Neutrophil gelatinase-associated lipocalin (NGAL) is produced in response to inflammation in horses, but it has not yet been investigated in horses with abdominal disease.

Objective: NGAL concentrations in serum and peritoneal fluid (PF) are increased in abdominal/gastro-intestinal inflammatory conditions.

Methods: Retrospective study of 270 horses admitted with acute abdominal disease (simple obstructions [n = 43], strangulating obstructions [n = 104], inflammatory abdominal disease [n = 99], non-strangulating intestinal infarctions [NSII, n = 24]) and nine healthy control horses. Data were retrieved from medical records and serum and PF samples were available from a biobank. NGAL was measured by ELISA.

Results: Horses with inflammatory abdominal disease and NSII had significantly higher serum and PF concentrations of NGAL than the other groups. PF NGAL concentrations in horses with NSII were higher than in horses with inflammatory abdominal disease. Serum concentrations of NGAL were lower in horses with <4 h of preadmission duration of colic than horses with longer duration of disease.

Conclusions: NGAL may aid the clinical decision-making in horses with severe colic by differentiating horses in need of immediate surgery (strangulating obstructions) from those needing medical therapy (inflammatory intestinal disease, e.g. enterocolitis). Assessment of NGAL seemed to be particularly useful in PF, where concentrations differed in horses with intestinal inflammation and horses with NSII. Horses with NSII are difficult to diagnose, as clinical signs and clinicopathological changes are non-specific. Use of NGAL may thus facilitate early diagnosis and surgical intervention, which is likely to improve the outcome in this group of patients.