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 Swine Dysentery Swine dysentery is a mucohemorrhagic diarrheal disease of pigs that is limited to the large intestine. Swine dysentery is most often observed in growing-finishing pigs and is associated with... read more , salmonellosis Salmonellosis in Animals read more , proliferative enteropathy Porcine Proliferative Enteropathy Porcine proliferative enteropathy is a common diarrheal disease of growing-finishing pigs and young breeding pigs, characterized by hyperplasia and inflammation of the jejunum, ileum, cecum... read more , or intestinal spirochetosis Intestinal Spirochetosis in Pigs Intestinal spirochetosis is a disease limited to the large intestine that commonly manifests as a mucoid diarrhea in grower-finisher pigs. Disease is considerably less severe than what is observed... read more . 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.