The prevalence of lameness and diversity of serogroups of Dichelobacter nodosus in sheep in England

Lameness in sheep is a significant problem in the UK, and footrot, caused by Dichelobacter nodosus, is the most common cause. A recent reduction in the prevalence of lameness between 2004 and 2013 was associated with increased use of best practice managements by farmers. A prevalence of < 2% lameness is achievable with current best practice managements, and is a target set by the Farm Animal Welfare Council for 2021. Vaccination is a preferred management by farmers, and ideally would be fully effective, preventing lameness and saving farmer time. The commercial multivalent vaccine reduces the prevalence of lameness by 20%. Mono- /bivalent vaccines are more effective, but only against homologous serogroups. \n \nA cohort of 164 English sheep farmers completed questionnaires regarding the prevalence of, and managements for, lameness in their flock, and submitted interdigital swabs from eight sheep. There was an increase in the prevalence of lameness in ewes in England in 2015 compared to 2013, which was associated with a decrease in the proportion of farmers treating all lame sheep within three days, despite the increased uptake of flock-level best practice managements. Prompt treatment (< 3 days) of all lame sheep will have the greatest impact on reducing the prevalence of lameness in England. All serogroups A – I were detected in England, at different prevalence, but distributed randomly between flocks, and there was heterogeneity in the serogroup communities between flocks. It is unlikely that a footrot vaccine tailored for England will be more effective than the commercial vaccine, as many flocks will not be protected. Tailored flock-specific vaccines may be more effective, but their feasibility in England will have to investigated. An improved vaccine is likely to be readily accepted by farmers, but knowledge transfer needs to focus on prompt treatment (< 3 days) of all lame sheep.