33rd Annual Scientific Meeting proceedings

Introduction and Objective
To characterise acidic gastroesophageal reflux (GER) events in non-brachycephalic, hospitalised dogs without overt gastrointestinal disease, using prolonged oesophageal pH-monitoring following short total intravenous anaesthesia (TIVA). Data was collected to establish upper reference limits for parameters that describe GER.

Materials and Methods
Healthy, client-owned dogs presenting for elective orthopaedic surgery were sedated with intravenous methadone and medetomidine, followed by alfaxalone TIVA. The oesophageal dual pH-monitoring probe was placed trans-nasally with the caudal-most extent in the distal oesophagus. Dogs were unsedated during the recording period. A GER event represented oesophageal pH <4.0. Parameters reported included number of GER events, cumulative duration of GER events, duration of longest GER event and percentage cumulative oesophageal acid exposure.

Results
Thirty-two dogs were included, with a median age of 7 years (range 1-12). The probe was well tolerated during a median recording duration of 20.6 hours (range 13.6-29.3). Expelled regurgitation was not recorded in any dog. The median number of distal and proximal GER events per hour was 0.3 (range 0-4.3) and 0 (range 0-1), respectively. The median cumulative distal and proximal oesophageal acid exposure was 0.2% (range 0.3-9%) and 0% (range 0-1%) of the recording period, respectively. Estimated upper reference limits for distal and proximal GER per hour was 6.1 and 1.3, respectively. Estimated upper reference limits for cumulative distal and proximal oesophageal acid exposure was 5% and 2.4%, respectively.

Discussion and Conclusions
Dogs undergoing oesophageal pH-monitoring in similar settings with recorded values above these upper reference limits may have excessive GER.