A mixed methods study investigating approaches to lameness control and aetiologies of hoof disorders in sheep

Lameness in sheep is an important welfare concern causing financial loss through poor performance. The aims of this thesis were to determine the current lameness prevalence in UK sheep flocks, evaluate the strategies used by farmers to control lameness, and investigate the aetiologies of specific hoof disorders including poor conformation and white line disease (WLD). This thesis comprises of mixed methods research from an epidemiological approach. Firstly, a quantitative, cross-sectional investigation of UK sheep farmers (n = 532) identified mean flock percentage lameness to be 3.2%, where only the minority of farmers implemented all five control measures listed in the lameness Five-Point Plan (5PP). Whilst this study provided new evidence supporting the benefits of adopting 5PP measures, a follow-up qualitative study with sheep farmers (n = 12) revealed a complex range of intrinsic factors, social dynamics and influences, and physical resources, to affect their long-term implementation on farm. A longitudinal, repeated cross-sectional field survey of ewes (n = 400) in commercial flocks (n = 4) was then conducted over a 12-month period and highlighted three hoof conformation traits to have trait-specific risks. On a subsample of these ewes (n = 65), feet with misshapen or damaged soles and heels were more likely to covertly harbour Dichelobacter nodosus at higher loads than undamaged feet. Finally, WLD was widespread in ewes across all flocks studied, where a number of risk factors were identified documenting its multifaceted and multifactorial origin. Results from this thesis make a novel contribution to the understanding of lameness and hoof disorders in UK sheep flocks. Core findings highlight that whilst lameness is an intractable challenge to sheep farmers, improvements to lameness prevalence can be facilitated by tailoring control strategies to embrace farm heterogeneity, utilising data to evaluate the success of control plans, discontinuing suboptimal managements, and refining best-practice advice