Clinical features and outcome of 40 horses with mesodiverticular bands identified during exploratory laparotomy for management of acute colic.

Abstract

BACKGROUND: Mesodiverticular bands (MDBs) are an embryonic remnant of the vitelline artery. Information about the clinical significance of equine MDBs is currently limited. OBJECTIVES: To report the clinical features, surgical findings and outcomes of horses undergoing exploratory laparotomy where a MDB was identified. STUDY DESIGN: Retrospective case series. METHODS: Case records of horses undergoing exploratory laparotomy for colic over a 14-year period (2009-2022) were reviewed. MDBs identified at laparotomy were classified as the primary or contributory cause of abdominal pain, or as incidental. RESULTS: MDBs were identified in 40/1943 horses (2.1%) and 15 were primary (32.5%), 10 contributory (25%) and 15 incidental (32.5%). Horses with primary MDBs (median 2&#x2009;years, IQR 1-12) were significantly younger than horses with incidental MDBs (median 8&#x2009;years, IQR 6-16; P&#x2009;=&#x2009;0.01). MDBs were more likely to be incidental if located in the mid-jejunum (5/5) (P&#x2009;<&#x2009;0.001) or where a mesenteric pocket was absent (11/15) (P&#x2009;=&#x2009;0.01). Primary MDBs caused extra-mural obstruction due to mesenteric shortening (n&#x2009;=&#x2009;4), small intestinal entrapment within the MDB pocket (n&#x2009;=&#x2009;5) or in an adjacent mesenteric rent (n&#x2009;=&#x2009;4), and volvulus around the MDB (n&#x2009;=&#x2009;2), with intestinal resection required in 8/15 cases. For horses with primary MDBs, survival to hospital discharge was 60% overall (9/15) and 75% for horses that stood following anaesthesia (9/12) with 88.9% of cases discharged from hospital (8/9) surviving >1&#x2009;year. Excision of MDB tissue was not associated with complications but 3/4 non-incidental MDBs left in situ required relaparotomy to treat MDB-associated colic. MAIN LIMITATIONS: Retrospective single centre data. CONCLUSIONS: Most MDBs in horses undergoing surgical treatment of colic in this population were not incidental. MDB-associated colic was most commonly classified as strangulating obstruction, but non-strangulating extra-mural compression was also identified. Excision of MDB tissue should be undertaken where possible, particularly in non-incidental cases.