Lung surfactant function and composition in neonatal foals and adult horses.
Authors: Christmann Undine, Livesey Leanda C, Taintor Jennifer S, Waldridge Bryan M, Schumacher John, Grier Bonnie L, Hite R Duncan
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Lung Surfactant in Neonatal and Adult Horses Pulmonary surfactant composition and function differ substantially between neonatal and mature horses, yet little was known about the specific nature of these differences—a gap this 2006 study addressed by collecting bronchoalveolar lavage fluid from six adult horses, seven term foals (under 24 hours old), and four premature foals, then separating and analysing surfactant fractions for phospholipid and protein content using ultracentrifugation and high-performance liquid chromatography. Whilst total phospholipid concentrations in lavage fluid remained similar between age groups, term foals exhibited significantly lower protein content, markedly reduced phosphatidylglycerol levels, elevated phosphatidylinositol, and crucially, increased minimum surface tension in their crude surfactant pellets compared to adults. These compositional changes carry important implications for respiratory mechanics in the newborn period; elevated surface tension suggests reduced biophysical efficiency of the surfactant in reducing alveolar collapse during breathing, whilst alterations in phospholipid ratios—particularly the reduction in phosphatidylglycerol, a key antimicrobial component—may compromise the immunological defences of the developing equine lung. For practitioners managing neonatal foals, particularly those with respiratory distress or prematurity concerns, this work underscores why immature surfactant function may predispose young animals to pulmonary complications and highlights the importance of monitoring respiratory effort during the critical first hours of life.
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Practical Takeaways
- •Neonatal foals have inherently different lung surfactant composition and function than adult horses, which is a normal developmental adaptation rather than a deficiency
- •Understanding these normal age-related differences helps distinguish physiologic respiratory changes in healthy neonates from pathologic respiratory disease requiring intervention
- •The altered immunologic properties of neonatal surfactant may have implications for neonatal susceptibility to respiratory infections during the critical early postnatal period
Key Findings
- •BALF protein content was significantly decreased in term foals (<24 hours) compared to adult horses, while phospholipid content was similar
- •Phosphatidylglycerol was significantly decreased and phosphatidylinositol significantly increased in neonatal foal surfactant compared to adults
- •Minimum surface tension was significantly increased in term foal crude surfactant pellets, indicating altered biophysical function compared to adult horses
- •Compositional and functional differences in neonatal foal surfactant may influence both biophysical and immunologic functions