Development and assessment of management practices in a flock-specific lameness control plan: A stepped-wedge trial on 44 English sheep flocks

Abstract

Lameness in sheep has economic and welfare implications, including loss of ewe body condition, lower lambing percentages, and poor lamb growth rates. It costs the UK sheep industry around £80 million per year. The majority of lameness is caused by the infectious diseases footrot and contagious ovine digital dermatitis, with white line separation, white line abscesses, and toe granulomas also reported by farmers. Most sheep farmers in the UK have other enterprises and care for their flock part-time. A lameness control plan (LCP) consisting of 37 management practices that covered all aspects of control of lameness was developed for part-time sheep farmers. Testing of the LCP was done using a stepped-wedge trial design with 7 visits to 44 flocks in England over 18 months. Flocks had 100-500 breeding ewes. Locomotion scoring was carried out at every visit, and farmers were interviewed every 6 months to record management practices. Clinical significance of changes in prevalence of lameness within each flock was analysed using the reliable change index (RCI). Management practices associated with prevalence of lameness were assessed using a multi-level multivariable over-dispersed Poisson model. The geometric mean (GM) prevalence of lameness at the start of the trial was 7.3% (95% confidence interval(CI) = 6.3-8.3%). Flocks with a clinically significant lameness reduction had a GM prevalence of lameness of 4.6% (95% CI = 4.1-5.2%), while flocks with a clinically significant increase in lameness had a GM prevalence of 10.5% (95% CI = 9.4-11.6%). Always separating lame sheep at treatment (relative risk (RR) = 0.60, 95% CI = 0.43-0.84) and culling sheep lame ≥2 occasions in a year (RR = 0.75, 95% CI = 0.61-0.92) were associated with a significant reduction in lameness. Compared with not footbathing at all, footbathing sheep when there were outbreaks of interdigital dermatitis reduced lameness (RR = 0.85, 95% CI = 0.75-0.96), however, 'routine' footbathing was not associated with a reduction in lameness. Housing during the previous lambing period was associated with a higher prevalence of lameness (RR = 1.23, 95% CI = 1.04-1.46). Vaccination in flocks with period prevalence ≥10% did not significantly reduce their risk of lameness compared to lower prevalence flocks. In conclusion, separating lame sheep at treatment, culling sheep lame ≥2 occasions per year, and only using a footbath to treat outbreaks of interdigital dermatitis are flock managements that contribute to improved control of lameness in flocks with part-time farmers.

Serogroups of Dichelobacter nodosus, the cause of footrot in sheep, are randomly distributed across England

“…Replies were received between 09/02/2016-30/06/2016 from 192/722 (26.6%) farmers who agreed to participate. An additional 18 farmers who had participated in the original study 4 and were participating in a separate clinical trial 32 were recruited. There was no difference in the proportion of D. nodosus positive swabs or the number of serogroups detected from the swabs from the surveyed farms and the clinical trial (Table 4), so data were combined and are presented together.…”

“…The liquid was spun off in a centrifuge and split into two aliquots, with one aliquot used for this project. The responses to the questionnaire for the farmers participating in the clinical trial 32 were retrieved from a more detailed questionnaire conducted as part of that study.…”

“…Kruskal-Wallis tests were used to investigate whether flock size, the prevalence of lameness or the prevalence of Table 4. The number and percentage of swabs by disease state by 146 postal flocks and 18 clinical trial flocks 32 . 60% of postal swabs were D. nodosus positive and 58% of clinical trial swabs.…”

Management Practices Associated With Prevalence of Lameness in Lambs in 2012–2013 in 1,271 English Sheep Flocks

“…In observational studies, recognition of mildly lame sheep (5,10), treatment of all lame sheep within 3 days of onset of lameness, inspection and isolation of brought-in sheep, vaccination against footrot, selecting replacement breeding ewes from never-lame mothers (5), separating lame sheep at treatment (15,16), culling sheep lame twice or more in a year (16), and not practicing routine foot trimming or routine footbathing (5,10,16) contribute to low flock prevalence of LiE.…”

Footbathing, formalin and foot trimming: The 3Fs associated with granulomas and shelly hoof in sheep

“…There is a body of published evidence that routine foot trimming and routine footbathing are associated with a higher prevalence of all lameness. Treating individual sheep lame with footrot rather than incorporating foot trimming and footbathing into routine flock management protocols reduces the prevalence of footrot (Kaler and Green, 2009;Winter et al, 2015;Witt and Green 2018). The only evidence of benefit from footbathing is for the treatment of interdigital dermatitis (Clifton and Green, 2016).…”