Risk factors associated with farmer-estimated ovine lameness and contagious ovine digital dermatitis

Abstract Background Lameness reduces flock productivity due to its impact on production efficiency and animal welfare coupled with the associated treatment and preventative costs. Previous research conducted on ovine flock-level lameness in the Republic of Ireland (ROI) has reported a median farmer reported prevalence of 6.0%, with contagious ovine digital dermatitis (CODD) present on 47.0% of ROI sheep flocks. However, data is limited as to the management practices employed by ROI sheep farmers to control and prevent ovine lameness, and the association of these practices with increased levels of lameness. This study aimed to: (i) describe the preventative and control measures implemented by farmers to manage ovine lameness, ii) identify farm management factors associated with increased farmer estimated ovine lameness prevalence, and iii) determine management and environmental factors influencing the likelihood of CODD being present within flocks. Results A survey was conducted opportunistically via online and in person delivery. Three hundred and sixty-three survey responses were gathered in ROI between January 2023 and May 2024. Four penalised regression models were used to identify variables associated with lameness prevalence, and the presence of CODD within flocks. Among respondents, 47.5% reported an open flock policy (purchasing sheep other than replacement breeding rams); this was associated with increased flock lameness and higher likelihood of CODD presence. Only 18.1% of respondents reported the isolation of purchased sheep for the recommend period of ≥ four weeks. Delayed treatment was associated with increased farmer estimated lameness prevalence. Trimming for the treatment of infectious lameness was also associated with increased lameness prevalence. Larger flock size and location within Munster were associated with increased odds of CODD presence within flocks. Culling practices were not significantly associated with flock-level lameness prevalence or CODD presence. Conclusions An association was found between farmer reported management practices, lameness prevalence and the presence of CODD in ROI flocks. The findings demonstrate that best practice management of infectious lameness is inconsistently implemented across ROI flocks. A focus on improved biosecurity practices, prompt treatment of lame sheep and the avoidance of foot trimming may reduce lameness prevalence and limit CODD transmission whilst improving flock productivity and welfare standards.