Mesenteric rents in the ascending mesocolon as cause of colic -- a retrospective case series

The ventral and dorsal components of the ascending colon are adjoined by the ascending mesocolon, and few case reports have described congenital or acquired malformations of this structure. This case series reports the occurrence of large mesenteric rents of the ascending mesocolon ( Hernia mesocolica coli ascendentis ) in 6 adult horses diagnosed during exploratory laparotomy. Based on the history of the patients, the rents were most likely acquired. The rents were mainly located directly adjacent to the left dorsal colon, and without affecting the intestinal blood supply. The size of the defect varied between 20 and 80 cm, and in 5/6 cases it was a subacute or chronic rupture with rounded edges. Two different types of intestinal displacements in relation to the rent were found, with either a localized torsion of the dorsal colon or herniation of the pelvic flexure through the rent. In all cases, the intestine could be repositioned, and the rent was sutured. Despite some minor postoperative complications, the short- and long-term outcome was excellent. It was hypothesised that recurrent colon displacements or trauma elicited by an intrauterine foal may have been the cause of the rent in some of the cases.