title: Oesophageal lumen pH in yearling horses and effects of management and administration of omeprazole.
abstract: BACKGROUND
  In human subjects, arytenoid chondritis can be caused by chemical trauma of mucosa attributable to gastro-oesophageal reflux. Although a similar process may be involved in the aetiopathogenesis of arytenoid chondritis in horses, the oesophageal lumen pH in this species is poorly understood.
  
  
  OBJECTIVE
  To determine if gastro-oesophageal reflux occurs in horses by characterising oesophageal lumen pH.
  
  
  METHODS
  Blinded, randomised, placebo-controlled, crossover, experimental study.
  
  
  METHODS
  Luminal oesophageal pH in six yearling horses was recorded over four 24 h periods using an ambulatory pH recorder attached to a catheter with two electrodes (proximal and distal) inserted into the oesophagus. Recordings of pH were made during three management protocols. Initially, horses grazed in a paddock (Protocol A). Horses were then moved to stables to simulate sale preparation of Thoroughbred yearlings, and were given either omeprazole (Protocol B) or placebo paste (Protocol C) orally once per day. Protocol A was repeated for each horse (after a 13 day washout period) between Protocols B and C. Summary statistics described pH range and frequency of pH changes. Associations with predictor variables were investigated using linear mixed-effects models. Data are presented as the mean ± s.d.
  
  
  RESULTS
  Oesophageal lumen pH ranged from 4.90 to 9.70 (7.36 ± 0.27 and 7.18 ± 0.24 for the proximal and distal electrodes, respectively) and varied frequently (1.2 ± 0.9 changes/min and 0.8 ± 0.8 changes/min for the proximal and distal electrodes, respectively). Oesophageal lumen pH was associated with time since concentrate feeding, activity and time of day, but not with treatment of omeprazole.
  
  
  CONCLUSIONS
  A small number of horses were used and measurement periods were limited.
  
  
  CONCLUSIONS
  Gastro-oesophageal reflux occurs in clinically normal yearling horses. Although omeprazole had no detectable effect, oesophageal lumen pH recorded during this study did not fall within the therapeutic range of omeprazole.
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
authors.forename: C S
authors.initials: CS
authors.lastname: Wilson
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.|Graham Centre for Agricultural Innovation, Wagga Wagga, New South Wales, Australia.
authors.forename: V J
authors.initials: VJ
authors.lastname: Brookes
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
authors.forename: K J
authors.initials: KJ
authors.lastname: Hughes
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
authors.forename: G D
authors.identifier: http://orcid.org/0000-0002-1153-3772
authors.initials: GD
authors.lastname: Trope
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.
authors.forename: H
authors.initials: H
authors.lastname: Ip
authors.affiliation: School of Animal and Veterinary Sciences, Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales, Australia.|Graham Centre for Agricultural Innovation, Wagga Wagga, New South Wales, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Gunn
mesh_terms: D000822:Animal Husbandry; D000818:Animals; D018592:Cross-Over Studies; D004947:Esophagus / Q000502:physiology*; D006736:Horses / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D009853:Omeprazole / Q000008:administration & dosage / Q000494:pharmacology*; D054328:Proton Pump Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D054328:Proton Pump Inhibitors; D009853:Omeprazole
keywords: arytenoid chondritis; gastro-oesophageal reflux; horse; oesophageal pH