Haemorrhagic bowel syndrome in fattening pigs

Background: Haemorrhagic bowel syndrome (HBS) is a sporadically occurring disorder in fattening pigs, characterized by sudden death in combination with severe abdominal distension and intense red colouration of the intestine. Deep understanding of aetiology and pathogenesis of HBS are still lacking, although several risk factors are known. Case presentation: In a continuously stocked fattening farm with 1500 pigs and liquid feeding based on whey, the mortality rate increased from 1.7% to 3.5% during summer time. Sporadic sudden death of growing pigs occurred along with severe abdominal distension as the main sign in these animals. All batches arriving at the farm received in-feed medication with Tiamulin hydrogen fumarate (2 mg/kg body weight/day; according to the license for use in Switzerland) due to detection of Brachyspira hyodysenteriae in the past, although a partial sanitation had been conducted thereafter. No changes of the origins, housing and the feeding procedure were reported. A herd examination was conducted revealing a hygiene problem in the feeding system. For further diagnostics a necropsy was performed, showing a pale carcass with a bloated abdomen due to a haemorrhagic infarction of part of the small intestine caused by a mesenteric torsion. Furthermore, a feed analysis was conducted, revealing a pH-value of 5 in the liquid feed, and a severe contamination with Enterobacteriaceae was detected. Based on these examinations, HBS was diagnosed. Subsequently, the farmer controlled the pH-value of the liquid feed with formic acid, improved the cleaning procedure of the liquid feeding system and stopped the in-feed medication. Following the implementation of these measures, key performance indicators improved significantly, but 4 months later the same clinical manifestation occurred again. This time huge variations in the pH-value of the liquid feed between different feeding times were recorded and were attributed to improper mixing of the formic acid in the whey tank. After implementation of a technical solution to control the pH-value, the health status improved again. Conclusion: In the present case, it is likely that the cause of the clinical manifestation of HBS was a contamination of Enterobacteriaceae in the liquid feed facilitated by a hygiene problem in the feeding system, and a chronic dysbacteriosis of the intestinal tract due to the non-justified routine use of antimicrobials. Speculatively, the prophylactic antimicrobial treatment was unnecessary and might even have exacerbated the clinical problem.