Mucosal alterations in experimentally induced small intestinal strangulation obstruction in ponies.

Small intestinal strangulation obstruction (ISO) was produced in seven ponies (under pentobarbital-anesthesia) by arteriovenous ligation. Positive-pressure ventilation with room air was used to maintain arterial PCO2 at the initiation of the ISO. Biopsy materials obtained from affected intestines at various times were evaluated, using histopathologic examination and scanning electron microscopy. Mucosal and villus degeneration was graded 0 to V and compared with intestinal gross color, motility, and wall thickness. The mucosa at the tip of the villus was the first to be affected. Degeneration of mucosa continued from the villus tip to the base before villus lamina propria degeneration occurred. Degeneration of mucosa and lamina propria continued after the ligature was released, and evidence of reestablished perfusion and motility was seen.