Plasma alpha-fetoprotein in neonatal foals affected by prematurity, sepsis and neonatal encephalopathy

Alpha-fetoprotein (AFP) concentrations have been reported in healthy foals and proposed as a biomarker of sepsis in foals born from mares with experimentally induced placentitis. This study aimed to describe the diagnostic and prognostic value of plasma AFP in foals spontaneously affected by different diseases. The study included all foals less than 72 h old that were diagnosed with either: (1) prematurity (PRE), when born prior to 320 days of gestation with immature physical characteristics; (2) sepsis (SEP), in the presence of both positive blood culture and SIRS or (3) neonatal encephalopathy (NE), with evidence of hypoxic-ischemic injury. Data from healthy foals (H; n=20) were obtained from a previous study. Foals received a complete physical and hematochemical evaluation and blood culture sample collection at hospital admission. Forty-six foals with an average age of 16 h were enrolled and divided into: PRE group (n=7); SEP group (n=14); NE group (n=25). AFP was measured in plasma collected at admission using a commercially available immunoassay validated for horses. AFP was increased in foals in PRE, SEP and NE groups compared with healthy ones (P<0.001) but was not able to discriminate between different diseases and outcomes. Overall, AFP was negatively correlated with foal age (r=-0.6; P<0.001), foal weight (r=-0.3; P=0.048), monocytes count (r=-0.4; P=0.011) and SAA concentration (r=-0.4; P=0.011). AFP appears to be a useful but non-specific indicator of neonatal health, since it upregulates not only in the presence of SIRS and bacteremia, but also during prematurity and hypoxic-ischemic injury.