GASTROESOPHAGEAL REFLUX DURING ANESTHESIA IN THE DOG - THE EFFECT OF AGE, POSITIONING AND TYPE OF SURGICAL-PROCEDURE

Lower oesophageal pH was monitored in 270 dogs under anaesthesia. Ther e were 47 episodes of gastro-oesophageal reflux (17.4 per cent), most of which occurred shortly after the induction of anaesthesia. The refl uxate was usually acid (pH<4.0), but in four of the episodes (8.5 per cent) it was alkaline (pH>7.5). Gastric contents with a pH below 2.5 w ere refluxed on 27 occasions (10 per cent) for an average period of ab out 44 minutes. Regurgitation occurred in two of the dogs. Increased a ge seemed to be associated with an increased incidence of reflux and a n increased gastric acidity, Body position (sternal, dorsal and left o r right lateral) and the tilt of the body during surgery (horizontal o r tilted to an 8 degrees head-up or head-down position) had no influen ce on the incidence of gastro-oesophageal reflux. Dogs undergoing intr a-abdominal surgery had significantly more reflux episodes than dogs u ndergoing non-abdominal surgery.