Serum lactoferrin and immunoglobulin G concentrations in healthy or ill neonatal foals and healthy adult horses.
Authors: Barton Michelle Henry, Hurley David, Norton Natalie, Heusner Gary, Costa Lais, Jones Samuel, Byars Doug, Watanabe Kiyotaka
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Lactoferrin and Immunoglobulin G in Neonatal Foal Health Lactoferrin, a colostral antimicrobial protein, has been proposed as a marker of passive transfer adequacy in neonatal foals, but its clinical utility relative to the established immunoglobulin G (IgG) benchmark remained unclear. This investigation compared serum lactoferrin and IgG concentrations across healthy neonates (n = 16), healthy adults (n = 10), and critically ill foals suspected of sepsis (n = 111), measuring both proteins via enzyme-linked immunosorbent assay and single radial immunodiffusion respectively, alongside neutrophil counts and sepsis scores. Following colostrum ingestion, healthy foals demonstrated dramatic increases in both serum IgG (2,921 ± 245 mg/dL versus 18 ± 2 at birth) and lactoferrin (445 ± 63 ng/mL versus 249 ± 39), with these parameters positively correlated only in the healthy cohort; however, whilst serum IgG concentrations were significantly lower in ill foals and specifically predictive of sepsis and mortality, lactoferrin showed no such discriminatory value, and neutropenic ill foals demonstrated particularly depressed lactoferrin levels. Although both proteins reflect passive transfer success in healthy neonates, serum IgG emerges as the superior prognostic indicator in suspected neonatal sepsis, suggesting that current IgG-focused assessment protocols remain the appropriate standard for clinical decision-making rather than supplementation with lactoferrin measurement in acute cases.
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Practical Takeaways
- •While lactoferrin increases in foal serum after colostrum intake, serum IgG concentration is a better clinical indicator of sepsis risk and survival in sick foals than lactoferrin alone
- •Measurement of serum IgG remains the more reliable prognostic marker for neonatal foal sepsis; lactoferrin adds limited additional predictive value in clinical assessment
- •Ensure adequate colostrum intake in neonates, but recognize that IgG monitoring is essential for identifying at-risk foals—lactoferrin measurement may not improve clinical decision-making
Key Findings
- •Mean colostral lactoferrin concentration was 21.7 μg/mL, with serum lactoferrin increasing from 249±39 ng/mL at birth to 445±63 ng/mL by 1-3 days in healthy foals
- •Serum IgG and lactoferrin concentrations were significantly correlated only in healthy foals, not in ill foals
- •Serum lactoferrin concentrations were significantly lower in ill neutropenic foals, but only serum IgG was significantly associated with sepsis score and survival outcomes
- •Plasma lactoferrin concentrations were significantly lower than serum concentrations, though the values were correlated