Evidence for surfactant contributing to the gastric mucosal barrier of the horse.
Authors: Ethell M T, Hodgson D R, Hills B A
Journal: Equine veterinary journal
Summary
The equine gastric mucosa possesses a distinctly hydrophobic surface—demonstrated by contact angle measurements of 78.0° in glandular tissue, significantly higher than the duodenum's 33.4°—a property imparted by phospholipid surfactant material observed in abundance throughout both squamous and glandular epithelium via electron microscopy. Ethell and colleagues examined fresh post-mortem gastric and duodenal samples from five horses using goniometry and specialised electron microscopy fixation techniques that preserve lipid ultrastructure, revealing osmiophilic phospholipid deposits lining the mucosal surface and intracellular canaliculi. This water-repellent lipid layer contributes meaningfully to the gastric mucosal barrier mechanism, functioning not merely as a passive coating but potentially as a physical obstruction against back-diffusion of acid into underlying tissues where other protective mechanisms are limited. Understanding this surfactant-mediated defence has implications for managing gastric ulceration: interventions that compromise mucosal phospholipid integrity—whether through prolonged fasting, systemic illness, or certain medications—may significantly impair this critical protective mechanism, whereas dietary and management approaches that support mucosal health may strengthen it. For practitioners, this research underscores why consistent feeding patterns and minimising physiological stress remain fundamental to gastric health, as the stomach relies on this lipid barrier working alongside conventional acid-buffering and mucus-secreting defences.
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Practical Takeaways
- •Understanding that the equine stomach has a specialized phospholipid barrier may inform strategies for managing gastric ulceration and acid-related conditions
- •Surfactant-based mechanisms of gastric protection suggest that management practices maintaining mucosal integrity (appropriate feeding, stress reduction) could preserve this critical defensive layer
- •This foundational research on normal gastric physiology provides a baseline for understanding pathological changes in horses with gastric disease
Key Findings
- •Equine gastric glandular mucosa contact angles (78.0 ± 11.0°) were significantly greater than duodenal mucosa (33.4 ± 8.7°, P=0.003), indicating greater hydrophobicity
- •Electron microscopy revealed abundant osmiophilic phospholipid material (surfactant) within both squamous and glandular gastric mucosae
- •Gastric squamous tissue contact angles (50.4 ± 4.5°) tended to be greater than duodenum, though not significantly
- •Surface-active phospholipids contribute to the water-repellent nature of the equine gastric mucosa and may protect against acid back-diffusion