Effect of paddock vs. stall housing on 24 hour gastric pH within the proximal and ventral equine stomach.

The research article explores the potential impact of different housing situations on the pH levels in various parts of a horse’s stomach. The study reveals that changing the housing status does not cause any significant alteration in the acid exposure within the horse’s stomach, contrasting prior suggestions that stall housing may be a risk factor for equine gastric ulcers.

Research Objective

• The primary objective of this research was to investigate whether different environmental situations, including grass paddock, stall alone, or stall with an adjacent companion, have a significant impact on the pH levels in the proximal and the ventral areas of a horse’s stomach.

Methodology

• The researchers used a group of six horses fitted with gastric cannulae, a tube used for nutrient delivery or monitoring of gas and pH levels, to measure intragastric pH levels. The horses went through each of the three environmental situations for 24 hours.
• The horses were kept on their usual diet of grass hay and grain twice a day throughout the experiment. The team continuously measured the intragastric pH levels for 72 hours, both at the lower oesophageal sphincter (proximal stomach) and through a pH probe in the gastric cannula (ventral stomach).

Results and Findings

• The research found that neither the proximal nor ventral 24-hour gastric pH significantly changed between the three environmental situations.
• Although there was a significant decrease in mean hourly proximal gastric pH between 01:00-09:00 compared to 13.00-20.00, irrespective of environmental situation, such variation did not occur in the ventral stomach. The change in housing status therefore did not affect acid exposure within either region of the equine stomach.
• The pH of the ventral stomach remained stable throughout the study, with the proximal pH exhibiting a 24-hour circadian pattern.

Research Conclusion

• This research concluded that changing the housing situation—from grass paddock to stall alone or stall with a companion—does not cause a significant alteration in the pH levels within the horse’s stomach. Despite changing environmental conditions, the pH in the ventral stomach remained stable throughout the study, with the circadian pattern being observed in the proximal pH. This contradicts any previous suggestions that stall housing may increase the risk of gastric ulcers in horses due to alteration of gastric pH.