Plasma UCHL-1 as a Biomarker of Brain Injury in Hospitalized Foals With Neonatal Encephalopathy

•Neonatal encephalopathy in foals can be difficult to definitively diagnose.•Plasma neuro biomarkers could help distinguish between NE and other conditions.•Plasma ubiquitin carboxyl-terminal hydrolase L1 (UCHL-1) was measured in hospitalized foals.•Biomarker concentrations were different between foals with NE and other diagnoses.•The diagnostic and prognostic value of this plasma biomarker was limited.•Plasma concentration of UCHL-1 did not adequately distinguish NE from sepsis. A plasma biomarker such as ubiquitin carboxyl-terminal hydrolase L1 (UCHL-1) to distinguish neonatal encephalopathy (NE) from other disorders and provide prognostic information would be useful for equine practitioners. In this prospective study, plasma UCHL-1 was measured in 331 hospitalized foals ≤4 days of age. Clinical diagnoses of neonatal encephalopathy only (NE group, n = 77), sepsis only (Sepsis group, n = 34), concurrent sepsis and NE (NE+Sepsis group, n = 85), or neither sepsis nor NE (Other group, n = 101) were made by the attending veterinarian. Plasma UCHL-1 concentrations were measured by ELISA. Differences between clinical diagnoses groups were evaluated and receiver operator curve (ROC) analysis was performed to assess diagnostic and prognostic performance. Median admission UCHL-1 concentration was significantly higher for NE (18.22 ng/mL; 7.93–37.43) and NE+Sepsis (17.42 ng/mL; 7.67–36.24) groups than Other foals (7.77 ng/mL; 3.92–22.76). Admission UCHL-1 was significantly higher in nonsurvivors (16.66 ng/mL; 6.89–34.84) than survivors (10.27 ng/mL; 5.82–29.94). Overall diagnostic performance of admission UCHL-1 concentration for NE diagnosis was determined (AUC 0.61; 95% confidence interval [CI] = 0.55–0.68); sensitivity and specificity for predicting NE were 73% and 49% respectively. Overall prognostic performance of time to lowest UCHL-1 concentration for predicting nonsurvival was determined (AUC 0.72; 95% CI = 0.65–0.79); sensitivity and specificity were 86% and 43% respectively. In this foal population, differences in plasma UCHL-1 concentrations were observed between foals with NE or NE with sepsis, and other diagnoses. The diagnostic and prognostic value of admission UCHL-1 concentration was limited.