ISCHEMIA-REPERFUSION INJURY OF THE ASCENDING COLON IN PONIES - A CORRELATIVE STUDY UTILIZING MICROVASCULAR HISTOPATHOLOGY AND CORROSION CASTING

Volvulus of the ascending colon (ACV) in the horse results in microvas cular injury and necrosis of the intestinal mucosa. This study investi gated the site and type of microvascular injury which occurs within th e mucosa and submucosa following ACV. Histopathology of volvulus treat ed ponies demonstrated mucosal necrosis with microvascular hemorrhage and thrombosis. Thrombi occurred within the subepithelial capillaries and edema and hemorrhage developed throughout the mucosa and submucosa . Vascular casts allowed 3-D viewing of samples obtained from the enti re pelvic flexure and demonstrated two distinct microvascular changes: 1) disruption of the colonic glandular capillary network occurred con comitantly with the mucosal injury, and 2) extensive endothelial leaka ge from the submucosal microvasculature contributes to edema formation . Thus, microcorrosion casting of the equine pelvic flexure provided a n effective means to characterize the location and severity of vascula r leakage and visualize the extent and severity of injury to the capil lary network not easily depicted by histopathology. Microvascular cast ing in conjunction with routine histopathology provided additional inf ormation on the pathomorphologic changes in this model of ischemia/rep erfusion injury.