Pre-operative feeding effects on post-anaesthetic colic and faecal output in horses

Post-anaesthetic colic (PAC) is a complication in horses undergoing general anaesthesia (GA). Various preoperative feeding strategies are used in equine practice, yet their impact on PAC remains unclear.

To identify perioperative risk factors associated with PAC and evaluate the influence of preoperative fasting on PAC prevalence and faecal output.

Retrospective cohort study.

Medical records of horses undergoing non-abdominal surgery under GA were reviewed. Horses were categorised into fasted and non-fasted groups based on their pre-anaesthetic feeding regimen. Multivariable logistic regression was used to identify variables associated with PAC. Differences in faecal output and water intake between groups were analysed using a two-tailed hypothesis test.

A total of 620 cases were included. Fasting (odds ratio [OR] 2.7, 95% CI 1.4-5.5, p = 0.005), increased surgery duration (per minute) (OR 1.01, 95% CI 1.002-1.02, p = 0.017) and increasing age (OR 1.08, 95% CI 1.02-1.15, p = 0.012) were significantly associated with PAC. Non-fasted horses passed significantly more manure post-operatively. Median (IQR) manure production per hour was 0.44 (0.31-0.61) piles in non-fasted versus 0.38 (0.25-0.50) piles in fasted horses during the first 24 h post-anaesthesia (p < 0.001) and 0.53 (0.42-0.67) versus 0.50 (0.36-0.63) in the second 24 h post-anaesthesia (p = 0.04). Water intake 12 h pre-anaesthesia was also higher in non-fasted horses (1.02 [0.73-1.75] L/h) compared to fasted horses (0.88 [0.53-1.75] L/h; p < 0.001).

Poor overall accuracy of the predictive model obtained. The retrospective design of the study may introduce bias due to possible inconsistencies in medical records.

Pre-operative fasting was associated with increased risk of PAC and reduced faecal output in horses. These findings support reconsidering fasting practices in equine anaesthesia.