title: Effect of paddock vs. stall housing on 24 hour gastric pH within the proximal and ventral equine stomach.
abstract: BACKGROUND
  Stall housing has been suggested as a risk factor for ulcer development in the equine stomach; however, the exact pathogenesis for this has not been established.
  
  
  OBJECTIVE
  To investigate the effect of 3 environmental situations (grass paddock, stall alone or stall with adjacent companion) on pH in the proximal and the ventral stomach.
  
  
  METHODS
  Six horses with permanently implanted gastric cannulae were used in a randomised, cross-over, block design. Each horse rotated through each of three 24 h environmental situations. Horses remained on their normal diet (grass hay ad libitum and grain b.i.d.) throughout the study. Intragastric pH was measured continuously for 72 h just inside the lower oesophageal sphincter (proximal stomach) and via a pH probe in the gastric cannula (ventral stomach).
  
  
  RESULTS
  Neither proximal nor ventral 24 h gastric pH changed significantly between the 3 environmental situations. Mean hourly proximal gastric pH decreased significantly in the interval from 01.00-09.00 h compared to the interval from 13.00-20.00 h, regardless of environmental situation. Median hourly proximal pH only differed in the interval from 06.00-07.00 h compared to the interval 14.00-19.00 h. Neither mean nor median hourly ventral gastric pH varied significantly with the time of day.
  
  
  CONCLUSIONS
  The change in housing status used in the current study did not affect acid exposure within either region of the equine stomach. The pH in the ventral stomach was uniformly stable throughout the study, while the proximal pH demonstrated a 24 h circadian pattern.
authors.affiliation: Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Dyrlaegevej 48, Frederiksberg C, Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Husted
authors.forename: L C
authors.initials: LC
authors.lastname: Sanchez
authors.forename: S N
authors.initials: SN
authors.lastname: Olsen
authors.forename: K E
authors.initials: KE
authors.lastname: Baptiste
authors.forename: A M
authors.initials: AM
authors.lastname: Merritt
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002940:Circadian Rhythm; D018592:Cross-Over Studies; D005260:Female; D005744:Gastric Acid / Q000502:physiology*; D005745:Gastric Acidity Determination / Q000662:veterinary*; D005753:Gastric Mucosa / Q000473:pathology; D006734:Horse Diseases / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D006736:Horses; D006799:Housing, Animal; D006863:Hydrogen-Ion Concentration; D008297:Male; D012307:Risk Factors; D013276:Stomach Ulcer / Q000453:epidemiology / Q000209:etiology / Q000473:pathology / Q000662:veterinary*