BACKGROUND: Anastomotic failure is one of the most frequent complications in rectal surgery. The present study aims to elucidate the effect of intraoperative lavage with short chain fatty acids (SCFAs) on rectal anastomosis of rats receiving corticosteroids.METHODS: Fifty male Wistar rats were divided into five groups. Group A (control group, without lavage and medication), group B (lavage with saline solution and no medication), group C (lavage with SCFAs and no medication), group D (lavage with saline solution and injection of 30mg/kg methylprednisolone 7 days pre-operatively and 4 days post-operatively), group E (lavage with a SCFAs and methylprednisolone). On the 4(th) postoperative day the animals were sacrificed and bursting pressure of the anastomosis, CRP, IL-6 and TNF-a were measured.RESULTS: Kruskal-Wallis variance analysis showed statistically significant differences between the groups (p<0.001). The bursting pressure of the anastomosis was lower in groups B and D, while it was higher in group C. TNF-a values displayed differences between group D and groups A, C, E.CONCLUSIONS: Intraoperative lavage with SCFAs increases anastomotic strength by increasing the bursting pressure of anastomosis in rats receiving corticosteroid, while lavage with saline solution decreases it. Rectal irrigation with short-chain fatty acids may improve anastomotic healing, especially in patients receiving corticosteroids.