Effect of the duration of food withholding prior to anesthesia on gastroesophageal reflux and regurgitation in healthy dogs undergoing elective orthopedic surgery.

OBJECTIVE To compare the incidence of and risk factors for gastroesophageal reflux (GER) and regurgitation associated with preanesthetic food withholding for periods of 18 hours (overnight) and 3 hours in healthy dogs undergoing elective orthopedic surgery. ANIMALS 82 healthy (American Society of Anesthesiologists physical status classification I or II) client-owned dogs. PROCEDURES Food was withheld for 18 hours (18-hour group [n = 41]) or each dog was allowed to consume half its daily ration of canned food approximately 3 hours (3-hour group [n = 41]) prior to induction of anesthesia. In each anesthetized dog, a pH catheter was introduced through the oropharynx into the distal portion of the esophagus; the pH was continuously recorded throughout the period of anesthesia. Gastroesophageal reflux was defined as pH < 4.0. RESULTS Gastroesophageal reflux was significantly associated with age, dorsal recumbency, and duration of preanesthetic food withholding. Regurgitation was significantly associated with duration of GER and duration of preanesthetic food withholding. During anesthesia, 25 (61%) dogs in the 3-hour group had GER and 12 (48%) of those dogs regurgitated gastric content; 18 (43.9%) dogs in the 18-hour group had GER and 2 (11.1%) of those dogs regurgitated gastric content. The mean lowest pH measured in the refluxate in the 3-hour group (2.3) was significantly greater than that in the 18-hour group (1.3). CONCLUSIONS AND CLINICAL RELEVANCE Among the study dogs undergoing orthopedic surgery, consumption of a light meal 3 hours prior to anesthesia was associated with significantly greater odds of reflux and regurgitation, compared with overnight food withholding.