Successful <em>Brachyspira hyodysenteriae</em> Eradication Through a Combined Approach of a Zinc Chelate Treatment and Adapted Management Measures

Brachyspira hyodysenteriae is the primary cause of swine dysentery, characterized by bloody to mucoid diarrhea due to mucohaemorhagic colitis in pigs. The disease primarily affects pigs during the growth and finishing stage. Control and prevention of B. hyodysenteriae consists of administration of antimicrobial drugs, besides management and adapted feeding strategies. A worldwide re-emergence of the disease has recently been reported with an increasing number of isolates demonstrating decreased susceptibility to several crucially important antimicrobials in the control of swine dysentery. This compromises the possibilities to eradicate B. hyodysenteriae from infected swine farms. A novel non-antibiotic zinc chelate has been reported to demonstrate positive effects on fecal quality and consistency, general clinical signs, average daily weight gain and B. hyodysenteriae excretion during and after a 6-day oral treatment. The objective of the present study was to evaluate the zinc chelate (IntraDysovinol® 499 mg/ml; IntraCare) within an eradication schedule with naturally occurring swine dysentery due to B. hyodysenteriae resistant to pleuromutilins under field conditions in Belgium. We evaluated a 14-day treatment schedule combined with alternative management measures (including partial depopulation of post-weaning facilities and improved external and internal biosecurity measures) and thorough cleaning and disinfection (including 2% NaOH) of the buildings and the sows from day 7 of treatment onwards. This alternative approach for B. hyodysenteriae eradication was evaluated on 18 swine farms over a 5-year period. All enrolled eradication programs were evaluated as successful at least 6-9 months after the finalization of the protocol. In conclusion, the zinc chelate product has an excellent potential for application within an eradication protocol of B. hyodysenteriae that were diagnosed resistant to pleuromutilins. The combined approach of zinc chelate treatment and alternative management measures demonstrated to be successful in the eradication of farrow-to-wean, farrow-to-finish and finishing swine farms under field conditions in Belgium.