Case Series of 23 Mesodiverticular Bands Identified at Laparotomy; Clinical Features and Outcome

Background: Mesodiverticular bands (MDB) are an embryonic remnant of the vitelline artery and may cause small intestinal (SI) obstruction or be an incidental finding at laparotomy. Limited information exists about MDB in the literature. 
Objectives: To report the clinical findings and outcome of horses identified with MDB at laparotomy. 
Study design: Retrospective case series. 
Methods: Electronic hospital records were searched over a 10-year period (2011-2021); data collected included signalment, clinical findings at presentation, surgical findings, treatment and outcome. MDB were classified as incidental or the primary cause of the colic based on surgical reports. 
Results: Twenty- three MBD were identified representing approximately 1.9% of all laparotomies. Fourteen (61%) were considered primary and 9 (39%) incidental. Most were located in the distal jejunum (19; 83%) with four in the mid-jejunum. There was no difference in mean age between incidental (9.3 years) and primary (7.1 years) MDB (p = 0.31) but all horses <3 years old were primary cases. Distended SI was identified pre-operatively in 12/14 of primary MDB cases. Primary MDB resulted in a strangulating obstruction in 10 cases (71%) and non-strangulating obstruction in 4 cases (29%). Intestinal compromise was severe in 8/14 primary cases; 3 of these were euthanased during surgery and 5 underwent SI resection. In the remaining cases, 5 had MDB resection only and one horse had SI decompression only. Of the 11 recovered primary MDB cases, 7 survived to hospital discharge (63.6%). For the incidental cases, MDB resection was performed in 6/9 cases and left in situ in 3/9. 
Main limitations: Data based from one hospital; missing data for some cases. 
Conclusions: Most MDB identified at laparotomy are the primary cause of colic signs, particularly in younger horses, and are usually located in the distal jejunum. Strangulating obstruction is common in these cases but outcome to hospital discharge is good. 
Ethical animal research: Research ethics committee oversight not required by this congress: retrospective data collection. 
Informed consent: Not stated. 
Competing interests: None declared. 
Sources of funding: None.

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