Background: Neutrophil gelatinase–associated lipocalin (NGAL) is a glycoprotein involved in immune responses and inflammation, with established diagnostic utility in acute kidney injury (AKI) and systemic diseases. However, reference values for NGAL in healthy horses, particularly the Turkmen breed, remain poorly defined. Aims/Objective: This study aimed to establish reference values for serum NGAL concentrations in healthy Turkmen horses and to evaluate the influence of age, sex, pregnancy status and physical activity on its levels, as well as its correlations with haematological and serum biochemical variables. Methods: Serum samples were collected from 90 clinically healthy Turkmen horses, categorized by age (<2 years, 2–8 years, >8 years), sex (male, female and castrated), pregnancy status and physical activity levels. NGAL concentrations were measured using enzyme-linked immunosorbent assay (ELISA), and statistical analyses were performed to assess associations with physiological factors. Results: The median serum NGAL concentration was 0.9 ng/mL, with 2.5th and 97.5th percentiles of 0.38 and 2.55 ng/mL, respectively. No significant differences in NGAL levels were observed between sexes or age groups, although horses aged <2 years exhibited the highest median NGAL concentration (1.04 ng/mL). Pregnancy and physical activity were associated with slightly higher NGAL levels, but these differences were not statistically significant (p > 0.05). This study provides the first reference values for serum NGAL in healthy Turkmen horses, highlighting its potential diagnostic relevance in monitoring physiological factors such as pregnancy and activity. Conclusions: Further research is needed to explore NGAL’s role in equine renal health and systemic diseases and to evaluate its utility in combination with other biomarkers for an early detection of inflammatory conditions.

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