BackgroundBrachyspira hyodysenteriae infection in pigs (‘swine dysentery’) leads to decreased feed conversion, growth losses and mortality. Current countermeasures have the downside of antibiotic resistance (antibiotics) and ecotoxicity (zinc oxide). The aim of this study was to evaluate the effect of a novel zinc chelate (Intra Dysovinol (ID)) on clinical signs of swine dysentery and shedding of B hyodysenteriae under field conditions.MethodsIn a randomised, double-blinded, controlled trial under Good Clinical Practice on two commercial farms, 58 B hyodysenteriae positive pigs from 16 pens received drinking water containing ID, or placebo, during six consecutive days. Faecal quality (consistency, colour, additions) was scored and faeces were analysed for presence of B hyodysenteriae by PCR. ID treatment positively affected faecal quality (consistency) and daily growth rates.ResultsAt the last treatment day, B hyodysenteriae was not detectable in the faeces of any of the ID-treated animals, while all placebo animals remained B hyodysenteriae positive by PCR. All ID-treated animals recovered, while 5 placebo-treated animals died and 12 placebo pigs required additional treatment before the end of the study (up to 14 days after treatment start).ConclusionThis non-antibiotic treatment stopped the clinical signs and shedding of B hyodysenteriae in naturally infected pigs.

Background: Brachyspira hyodysenteriae is the primary cause of swine dysentery, characterized by bloody to mucoid diarrhea due to mucohaemorhagic colitis in pigs and primarily affects pigs during the grow/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. 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 (Intra Dysovinol ® 499 mg/ml (ID); Elanco) on naturally occurring swine dysentery due to B. hyodysenteriae under field conditions in the Netherlands. Results: Oral administration of zinc chelate resulted in improvement of general clinical signs from 3 days onwards in the ID-treated group combined with a significantly better total fecal score at 14 days post-treatment. Overall, average daily weight gain was better in the ID-treated group over the entire study period (0-14 days) and during the 8 days following the end of ID-treatment. A significant reduction (4.48 vs. 0.63 log 10 cfu/g feces; ID-treated vs. control) in B. hyodysenteriae excretion was observed during the 6-day treatment period with a high percentage of animals (58.3 vs. 12.3%; ID-treated vs. control) with no excretion of B. hyodysenteriae from their feces. No additional antimicrobial treatment was needed in the ID-treated group, whereas 35% of the pigs in the control group were treated with an antibiotic at least once. No mortality occurred in both groups. No adverse events were reported during and following the ID-treatment. Conclusions: Zinc chelateadministered as a Zn-Na 2-EDTA complexis a non-antibiotic treatment for swine dysentery that reduces B. hyodysenteriae shedding with 4.48 log 10 cfu/g feces within its 6-day treatment while improving general clinical signs (90.0 vs. 73.6% animals with normal score) and total fecal score within 2-4 days following administration in naturally infected pigs. The positive effects of ID treatment remain for at least 8 days after cessation of oral ID therapy. Pigs remaining in a highly contaminated environment may be re-infected following the end of ID treatment, however, this is not different to standard antimicrobial therapy. Therefore, control of swine dysentery should combine an efficacious treatment with additional management practices to reduce the environmental infection pressure in order to limit re-infection as much as possible. The ID treatment resulted in a higher growth rate and improved general health, whereas no mortality was observed and no additional therapeutic treatments were necessary in contrast to the c...