Hemorrhagic bowel syndrome affects rapidly growing swine 4–6 months old. Pigs die suddenly without evidence of diarrhea; however, on postmortem examination, the small intestine is thin-walled and filled with either clotted or unclotted blood. The large intestine usually contains tarry fecal material but no lesions suggestive of swine dysentery, salmonellosis, proliferative enteropathy, or intestinal spirochetosis. The syndrome can be prevented by administration of either bacitracin or chlortetracycline in the feed. A peracute form of proliferative enteropathy may have similar clinical and gross lesions; however, histologic evaluation and PCR assay on intestinal contents will discern the presence or absence of epithelial proliferation and Lawsonia intracellularis.
The cause of hemorrhagic bowel syndrome is unknown. Predisposing factors may include vigorous exercise, handling, fighting, piling, or irregular feeding. Highly fermentable rations, particularly if fed in liquid form, may increase the incidence of disease. At postmortem examination, lesions are similar to those of venous infarction secondary to mesenteric torsion; however, no torsion is observed. It has been suggested that the condition may be due to partial torsion or that the torsion is resolved pre-mortem. Diagnosis is by exclusion of other causes of intestinal disease, as noted above, and the histopathologic observation of transmural hemorrhage in the intestine.
