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Comparison of footbathing and vaccination to control ovine footrot in an experimentally infected flock

Allworth, MB, Egerton, JR
Australian veterinary journal 2018 v.96 no.10 pp. 395-399
Dichelobacter nodosus, flocks, footrot, pastures, recombinant DNA, recombinant vaccines, sheep, vaccination, virulent strains, zinc sulfate
OBJECTIVE: Compare footbathing and vaccination for control of footrot during a transmission period in a sheep flock deliberately infected with multiple strains of Dichelobacter nodosus. METHODS: The strains included a known virulent strain, a benign strain and several intermediate strains. The resulting footrot was clinically intermediate. A total of 1450 Polwarth sheep aged 1–3 years were allocated to one of five treatment groups: untreated, weekly walkthrough zinc sulfate footbathing, 1‐hour stand‐in Footrite® footbathing every 3 weeks, vaccination with a commercial multivalent whole‐cell vaccine and vaccination with a novel recombinant DNA fimbrial vaccine. There were four replicates, in four paddocks. RESULTS: Of the untreated animals, 76% had footrot. Footbathing, either weekly or every 3 weeks, restricted the prevalence to 6/283 (2%; 97% effective) and 18/275 (6.5%; 91% effective), respectively. This was significantly lower than the prevalence in either the untreated or vaccinated group (P < 0.001). Weekly footbathing resulted in significantly fewer affected sheep than footbathing for 1 h every 3 weeks (P < 0.05). Vaccination with either whole‐cell or recombinant vaccines significantly (P < 0.001) reduced the prevalence ((142/280 (51%; 33% effective), 114/278 (41%; 46% effective) respectively), with the recombinant vaccine superior (P < 0.05) to whole‐cell vaccination. Significantly (P < 0.05) fewer 1‐year‐old sheep had footrot than older sheep. A single Footrite treatment reduced the prevalence to 12% (53/445) compared with a prevalence of 57% (27/47) for untreated sheep (79% effective). CONCLUSION: In this study footbathing was more effective than vaccination at controlling and treating multistrain footrot.