Treatment of clinical Brachyspira hyodysenteriae with zinc chelate in pigs: a blinded, randomised controlled trial

Abstract

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.

Evaluation of a zinc chelate on clinical swine dysentery under field conditions

“…In the current study, B. hyodysenteriae excretion did not completely disappear at SD6 in contrast to the results reported by Lammers et al (2019) [22]. Besides the above mentioned factors related to differences in housing and environmental infection pressure, basic differences in sampling approach and subsequent qPCR analysis were present.…”

“…This observation might be associated with the challenging housing circumstances of the pigs in the current study. In contrast to Lammers et al (2019) [22], who performed his trials under conventional Dutch housing conditions, the pigs in our trial were housed in a concept including a high-welfare environment, which implicates more than 80% solid flooring, partly (50%) bedded with straw, and only a very little slatted surface. These circumstances do not favour the evacuation of B. hyodysenteriae-infected feces throughout the study and might expose the pigs to moderate to high amounts of potentially contagious fecal material.…”

“…An in vivo feasibility study demonstrated a positive effect of the zinc chelate to fecal quality and consistency, general clinical signs and average daily weight gain (ADWG) in B. hyodysenteriae-infected animals. Moreover, at the last treatment day, B. hyodysenteriae was not detectable by qPCR in most of the treated animals [22]. Based on these promising in vitro and in vivo results, the goal of the present study was to assess the efficacy of the zinc chelate, formulated as the Veterinary Medicinal Product Intra Dysovinol ® 499 mg/ml (ID; Elanco, Greenfield, IN) in the treatment of clinical signs due to B. hyodysenteriae infection in pigs under more challenging field conditions.…”

“…Sample size calculations for a two-sided two-sample ttest were carried out in JMP 14.1 using the following parameters based on a previous field study with ID in the Netherlands [22]:…”

“…Chelation of zinc with an organic molecule to form a Zn-Na 2 -EDTAinstead of covalent binding of zinc to inorganic oxygenreduces its environmental impact [22]. In addition, previous in vitro (unpublished data) and in vivo studies [22] have demonstrated that the Zn-Na 2 -EDTA chelated complexin relatively low concentrationsis potentially able to reduce adverse effects due to B. hyodysenteriae infections in pigs. An in vivo feasibility study demonstrated a positive effect of the zinc chelate to fecal quality and consistency, general clinical signs and average daily weight gain (ADWG) in B. hyodysenteriae-infected animals.…”