Grossly, one sees aggregates of gas bubbles within any of the small intestinal layers, adjacent mesentery, and occasionally mesenteric lymph nodes. The associated inflammatory infiltrate is primarily composed of macrophages and giant cells with plasma cells and lymphocytes present in variable numbers. Intestinal emphysema is reported most frequently in pigs and less often in rabbits, chickens and sheep. Many of the gas-filled spaces are endothelial lined, and are presumed to be lymphatics. The cause is unknown and the condition produces no clinical signs.
Affected areas are crepitant when palpated.
The gaseous cysts sometimes contain clotted blood. Intestinal emphysema is occasionally seen in sheep with enterotoxemia. Pneumatosis cystoides intestinalis may be an asymptomatic incidental condition discovered during laparotomy, or it may be acute and fulminant when associated with necrotizing bacterial infections of the bowel. Hyperbaric oxygen treatment with a controlled diet and metronidazole successfully resolves the condition. A similar condition can be experimentally induced by Clostridium perfringens in guinea pigs and rats.