Vascular injury associated with naturally occurring strangulating obstructions of the equine large colon.

This study is about analyzing vascular injuries related to natural obstructions in the large colon of horses, with specific reference to ten equine cases euthanized due to severe colonic volvulus or twisting. The study found that even after surgically correcting the problem, the horses’ colon might not regain full health due to vascular damage including thrombosis.

Colonic Volvulus and Its Correction in Horses

• This research focuses on ten horses that had to be euthanized before, during, or after surgical procedures meant to correct severe volvulus of the large colon. Colonic volvulus, or twisting of the colon, is a life-threatening condition in horses which can cause obstruction and ischemic injury to the colon.
• The surgical correction involves untwisting the twisted large colon to restore its normal position and function. In this study, the observations from the surgery indicated a change in the color of the colonic serosa (outer layer of the colon) from blue-gray, blue or purple to a more normal pink in seven out of the ten horses after the colonic volvulus was corrected.

Postmortem Examination and Microangiography

• The study also involved post-mortem examinations including colonic microangiography, an imaging technique used to visualize the small blood vessels of the colon. This investigation revealed that while the serosa and the muscle layers of the colon regained their perfusion (blood flow), the innermost layer or mucosa did not.
• Consistently, the mucosa maintained a black or dark red appearance, indicating an unhealthy state due to limited perfusion brought about by thrombosis (blood clotting) in the muscularis mucosae (a thin layer of muscle tissue under the mucosa) and submucosa (the layer beneath the mucosa).

Colonic Vascular Damage Following Volvulus

• Further, the study shows evidence of thrombosis in the mesenteric colic vessels (vessels that supply the colon) in six horses. This indicates severe vascular damage associated with the twisting and untwisting of the large colon.
• The study concludes that such damage to the colonic vascular system, particularly thrombosis in the submucosal area, may pose significant limitations to the recovery of the colon’s health after surgical deceleration of volvulus. This could hint at the high risk and complexity of colonic volvulus in horses and the challenges of achieving full recovery after surgical intervention.