Stabling causes a significant increase in the pH of the equine airway.
Authors: Whittaker A G, Love S, Parkin T D H, Duz M, Hughes K J
Journal: Equine veterinary journal
Summary
# Editorial Summary: Stabling and Equine Airway pH Whittaker and colleagues used exhaled breath condensate (EBC) analysis to investigate how environmental factors influence airway pH in horses, addressing a gap in our understanding of respiratory homeostasis in this species. Horses were monitored longitudinally across different housing conditions, with ambient ammonia levels, EBC pH and exhaled ammonia measured using a simple, non-invasive protocol that proved highly repeatable. Stabling increased ambient ammonia concentrations by 100–200 parts per billion compared to pasture, which directly correlated with significant increases in both airway pH and exhaled ammonia (P = 0.002 and P = 0.013 respectively), though management practices within stables (feed type and bedding) did not significantly influence these parameters. These findings suggest that airway alkalinisation occurs in response to ammonia exposure, which may compromise the airway's innate defences and contribute to the elevated prevalence of respiratory disease in stabled horses. For practitioners, this underscores the importance of stable ventilation as a primary control measure—optimising air quality may be as clinically relevant as traditional management adjustments—and provides a measurable physiological mechanism linking housing conditions to respiratory health.
Read the full abstract on PubMed
Practical Takeaways
- •Stabling horses creates higher ammonia levels in the environment, which alters airway pH—consider ventilation improvements and bedding management to minimize ammonia buildup
- •Exhaled breath condensate pH measurement offers a noninvasive way to monitor airway health changes in response to management changes
- •Pasture turnout appears beneficial for maintaining normal airway pH; if stabling is necessary, focus on ammonia control through ventilation rather than relying on bedding type alone
Key Findings
- •Stabling increased ambient ammonia concentration by approximately 100-200 ppb compared to pasture (P < 0.001)
- •Increased ammonia exposure was associated with significant increases in exhaled breath condensate pH (P = 0.002)
- •Exhaled ammonia concentration increased significantly with stabling (P = 0.013)
- •Stable feed/bedding management type did not affect EBC pH or exhaled ammonia, though it influenced ambient ammonia concentration