Mesodiverticular bands as a cause of small intestinal strangulation and volvulus in the horse.

This research work investigates the cause of small intestinal strangulation and volvulus in horses, tracing it to an abnormality known as mesodiverticular band. Through cases of jejunal and ileal volvulus in three horses, the role of this anomaly and its involvement in intestinal conditions was examined.

Understanding the Mesodiverticular Bands

• A mesodiverticular band is an abnormal structure formed in the small intestines of horses. This was determined based on the cases of three horses involving the twisting (volvulus) of the jejunum and ileum, important parts of the horse’s small intestine.
• This unusual structure is attached to the jejunal mesentery (i.e., a fold that connects the jejunum to the posterior wall of the abdomen) also, forming one side of what is described as a triangular hernial sac. This sac is completed on the other side by the adjacent jejunal mesentery, creating a vulnerable spot.

Development of Small Intestinal Strangulation and Volvulus

• An incarceration (trapping) of a loop of small intestine in the hernial sac is seen as the initial step towards the rupture of the jejunal mesentery and subsequent small intestine strangulation. This arrest of the intestinal loop potentially precipitates a chain of cascaded events leading to serious complications in the horse’s digestive system.
• Furthermore, the rupture of the jejunal mesentery known as a mesenteric rent was pinpointed to be at the attachment site of the mesodiverticular band, which further enhances the complication.

Surgeries and Treatment

• In attempts to address these complications, surgical adjustments were successful in two of the three horses. This was performed via the resection (removing or cutting away) of the gangrenous or disease-affected intestine and then performing a jejunocecal anastomosis – a surgical connection between the jejunum and the cecum to ensure a bypass of the path between these two regions.
• However, the third horse had to be euthanized due to intestinal rupture and peritonitis, which is inflammation of the lining of the abdominal cavity. This highlights the severity of these conditions if left untreated.
• Furthermore, two mesodiverticular bands attached to the distal jejunum were found in a necropsy, or post-mortem examination, of a fourth horse underscoring their prevalence and potential danger.