Effect of age, feeding, and omeprazole administration on gastric tonometry in healthy neonatal foals.
Authors: Sanchez L C, Giguère S, Javsicas L H, Bier J, Walrond C J, Womble A Y
Journal: Journal of veterinary internal medicine
Summary
Gastric tonometry—measurement of intramucosal carbon dioxide tension—offers a non-invasive window into gastric mucosal perfusion in neonates, yet baseline values for healthy foals remain poorly characterised, limiting its clinical utility as a monitoring tool. Researchers tracked nine healthy foals at 1, 7, and 14 days of age under varying feeding states (baseline, immediately post-feeding, and after 1–2 hours fasting), measuring intramucosal PCO2 and calculating the intramucosal-arterial PCO2 difference (ΔCO2), whilst a separate cohort of eight foals received omeprazole to assess its influence on these parameters. Age and feeding substantially altered gastric tonometry values: postfeeding ΔCO2 was significantly lower than fasted measurements, and both baseline and postfeeding ΔCO2 increased with age, though fasting measurements showed no age-related change; omeprazole administration significantly elevated gastric pH, intramucosal PCO2, and ΔCO2 compared to untreated foals, with the fasting ΔCO2 reference interval proving remarkably wide (0–54 mmHg). The considerable physiological variability in neonatal gastric tonometry—particularly its amplification by acid-suppressive therapy—substantially constrains the clinical interpretation of individual measurements in foals, suggesting that whilst the technique may eventually prove valuable for identifying pathologically abnormal perfusion, establishing meaningful thresholds for clinical intervention remains challenging. Practitioners should recognise that omeprazole use in neonatal foals will materially elevate tonometric values, and that a single measurement without contextual clinical information carries limited diagnostic weight.
Read the full abstract on PubMed
Practical Takeaways
- •Gastric tonometry reference values in foals are age and feeding-dependent; interpretation must account for these variables and cannot be directly extrapolated from adult or human data
- •Omeprazole use in neonatal foals significantly alters gastric tonometry measurements, making this technique unreliable for clinical assessment when the drug is administered
- •The extremely wide reference intervals and high variability in DeltaCO2 limit the clinical utility of gastric tonometry as a standalone diagnostic tool in neonatal foals
Key Findings
- •Age and feeding significantly affected gastric intramucosal PCO2 (PgCO2) and intramucosal-arterial PCO2 difference (DeltaCO2), with postfeeding DeltaCO2 values significantly lower than fasted values
- •The 90% reference interval for DeltaCO2 after fasting was 0-54 mmHg, establishing baseline values for healthy neonatal foals
- •Omeprazole administration significantly increased gastric pH, DeltaCO2, and PgCO2 compared to control, resulting in extremely wide and variable reference intervals
- •Arterial PCO2 was not significantly affected by age, feeding, or omeprazole administration