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

"I didn't see a sheep": perspectives of lecturers and students at veterinary schools in Great Britain on learning about lameness in sheep

Introduction

Great Britain has over 15 million ewes. Lameness is one of the top three most economically important diseases for the sheep industry, costing about £80 million per annum. The prevalence of lameness reduced from 10% to 5% between 2004 and 2013 but further reduction is unlikely because many farmers and agricultural students still believe in, and use, ineffective practices to control lameness. Unfortunately, many veterinary practitioners consider themselves insufficiently knowledgeable to work confidently with sheep farmers, and many sheep farmers agree with them. Another route to improve control of lameness is to ensure that all new veterinary graduates are competent to advise farmers.

Methods

Our study investigated how veterinary students are taught about management of lameness in sheep. Ten lecturers from eight veterinary schools were interviewed, and 33 students from four veterinary schools participated in four focus groups; all were recorded, transcribed, and analysed using directed qualitative content analysis.

Results

Teaching time and opportunities for students to gain clinical experience of lameness were very limited. Students were not confident they could diagnose causes of lameness and listed many practices, including ineffective ones, to manage footrot.

Discussion

We conclude that GB veterinary students are graduating without evidence-based understanding and clinical experience necessary to advise farmers on management of lameness in sheep. Given the importance of lameness in sheep in GB we conclude that an alternative approach to education on lameness in sheep could help to ensure that new graduate veterinarians can contribute to control of lameness in sheep.

Prevalence and Temporal Dynamics of White Line Disease in Sheep: An Exploratory Investigation into Disease Distribution and Associated Risk Factors

Lameness in sheep is a global health, welfare and economic concern. White line disease (WLD), also known as shelly hoof, is a prevalent, non-infectious cause of lameness, characterised by the breakdown of the white line. Little is known about the predisposing factors, nor the individual disease dynamics over time. Our exploratory study aimed to investigate the prevalence and temporal dynamics of WLD, and the associated risk factors. Feet of 400 ewes from four UK commercial sheep farms were inspected for WLD at four time points across 12 months. The change in WLD state at foot-level (develop or recover) was calculated for three transition periods. We present WLD to be widespread, affecting 46.8% of foot-level and 76.6% of sheep-level observations. States in WLD changed over time, with feet readily developing and recovering from WLD within the study period. The presence of WLD at foot-level, the number of feet affected at sheep-level and dynamics in development and recovery were driven by a variety of foot-, sheep- and farm-level factors. We provide key insight into the multifaceted aetiology of WLD and corroborate previous studies demonstrating its multifactorial nature. Our study highlights an opportunity to reduce WLD prevalence and informs hypotheses for future prospective studies.

Multiple model triangulation to identify factors associated with lameness in British sheep flocks

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Multiple model triangulation identifies variables that are likely true positives.

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Triangulation increases confidence in which managements to recommend in practice.

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Effective management of ewes can lower prevalence of lameness in ewes and lambs.

Identification of factors associated with an outcome can be challenging when the number of explanatory variables is large in relation to the number of observations. Multiple model triangulation, where results from several model types are combined, improves the likelihood of identifying true predictor variables. The aim of this study was to use triangulation to identify covariates likely to be truly associated with the prevalence of lameness in sheep flocks in Great Britain.

Data were collected using a questionnaire sent to 3200 sheep farmers in Great Britain in 2018. The useable response rate was 14.1 %. The geometric mean prevalence of lameness was 1.4 % (95 % CI 1.2−1.7) for ewes, and 0.6 % (95 % CI 0.5−0.9) for lambs, however, approximately 60 % flocks had >2% prevalence of lameness in ewes.

Four model types were investigated, two generalised linear models (negative binomial and quasi-Poisson) built using stepwise selection, and two elastic net models (Poisson and Gaussian distributions) refined with selection stability estimation.

Triangulated covariates were those selected in three or all four models – 10 for ewes and 12 for lambs. Higher prevalence of lameness in ewes was associated with 5−100% feet bleeding during routine foot trimming compared with not foot trimming, footbathing the flock to treat severe footrot (SFR) and always using formalin in footbaths, both compared with not footbathing, using FootVax™ for <1 year compared with not using FootVax™, and never quarantining new or returning sheep to the farm for >3 weeks compared with always. Lower prevalence of lameness in ewes was associated with vaccinating with FootVax™ for >5 years compared with not vaccinating, peat soil compared with no peat soil, and having no lame ewes to treat.

Higher prevalence of lameness in lambs was associated with 5−100% feet bleeding during routine foot trimming, always foot trimming ewes with SFR, not knowingly selecting replacement ewes from ewes that were never lame compared with always, replacement sheep purchased and homebred compared with only homebred, treating lambs >3 days after recognition of lameness compared with 0-3 days and footbathing the flock to treat interdigital dermatitis compared with not footbathing at all. Lower prevalence of lameness in lambs was associated with peat soil, flocks in Scotland versus England, an altitude of >230−500 m compared with ≤230 m, never using antibiotic injection to treat lambs with SFR compared with always, and having no lame lambs to treat.

We conclude triangulation identified reliable management practices for farmers to implement to minimise lameness in sheep.

Characterisation of Dichelobacter nodosus on Misshapen and Damaged Ovine Feet: A Longitudinal Study of Four UK Sheep Flocks

Simple Summary

The bacterium Dichelobacter nodosus is the cause of footrot in sheep: a painful, contagious foot disease. Some sheep may be more susceptible to carrying D. nodosus on their feet, despite showing no signs of disease, and pose a risk to flock health and welfare. This study investigated whether misshapen or damaged feet (poor hoof conformation) were more likely to have D. nodosus present and in greater quantities than feet in good condition. Eighty-five ewes from four flocks were examined three times, on average, across a 12-month period. Poor hoof conformation traits were observed in over 92% of foot observations. Feet with poor sole and heel conformation were more likely to have higher quantities of D. nodosus than those in good conformation. Furthermore, on feet positive for D. nodosus, wall overgrowth contributed towards higher D. nodosus load. We highlight feet with aspects of poor conformation traits to covertly harbour D. nodosus. These feet could transmit D. nodosus to other feet of sheep. Increasing our understanding of D. nodosus infection is crucial in helping farmers improve management practices to reduce footrot.

Abstract

Dichelobacter nodosus is the causal agent of ovine footrot, a contagious disease of welfare and economic concern worldwide. Damaged feet may be subclinical carriers of D. nodosus and covertly spread infection. Accordingly, we evaluated the risk of misshapen and damaged feet on D. nodosus presence and load in four commercial UK sheep flocks. Foot-level observations and swabs (n = 972) were collected from ewes (n = 85) over 12 months. On average, ewes were sampled three times. Feet were inspected for disease and scored (good/poor) for three hoof conformation traits (sole and heel, wall, and wall overgrowth). Swabs were analysed for presence and load of D. nodosus, and mixed models were constructed. Poor hoof conformation traits were present in 92.5% of foot-level observations. Feet with poor sole and heel conformation were more likely to have higher D. nodosus loads (β = 0.19, 95% CI: 0.04–0.35) than those with good conformation. Furthermore, on feet positive for D. nodosus, wall overgrowth was associated with higher D. nodosus loads (β = 0.27, 95% CI: 0.01–0.52). Feet with aspects of poor conformation covertly harbour D. nodosus and are a source of infection. Flock management should be guided by hoof conformation to reduce disease challenge.

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

The evidence base for management practices associated with low prevalence of lameness in ewes is robust. Current best practice is prompt treatment of even mildly lame sheep with parenteral and topical antibiotics with no routine or therapeutic foot trimming and avoiding routine footbathing. To date, comparatively little is known about management of lameness in lambs. Data came from a questionnaire completed by 1,271 English sheep farmers in 2013. Latent class (LC) analyses were used to investigate associations between treatment of footrot and geometric mean flock prevalence of lameness (GMPL) in lambs and ewes, with multinomial models used to investigate effects of flock management with treatment. Different flock typologies were identified for ewes and lambs. In both ewe and lamb models, there was an LC (1) with GMPL <2%, where infectious causes of lameness were rare, and farmers rarely treated lame animals. There was a second LC in ewes only (GMPL 3.2%) where infectious causes of lameness were present but farmers followed "best practice" and apparently controlled lameness. In other typologies, farmers did not use best practice and had higher GMPL than LC1 (3.9-4.2% and 2.8-3.5%, respectively). In the multinomial model, farmers were more likely to use parenteral antibiotics to treat lambs when more than 2-5% of lambs were lame compared with ≤2%. Once >10% of lambs were lame, while farmers were likely to use parenteral antibiotics, only sheep with locomotion score >2 were considered lame, leaving lame sheep untreated, potentially allowing spread of footrot. These farmers also used poor practices of routine foot trimming and footbathing, delayed culling, and poor biosecurity. We conclude there are no managements beneficial to manage lameness in lambs different from those for ewes; however, currently lameness in lambs is not treated using "best practice." In flocks with <2% prevalence of all lameness, where infectious causes of lameness were rare, farmers rarely treated lame animals but also did not practice poor managements of routine foot trimming or footbathing. If more farmers adopted "best practice" in ewes and lambs, the prevalence of lameness in lambs could be reduced to <2%, antibiotic use would be reduced, and sheep welfare would be improved.

Uptake of the lameness Five-Point Plan and its association with farmer-reported lameness prevalence: A cross-sectional study of 532 UK sheep farmers

The aims of this research were to determine the uptake of a national strategy to reduce lameness in the UK flock, known as the Five-Point Plan (5 P P); explore the association between footrot vaccination (Footvax®) use and 5 P P adoption; investigate the management practices associated with farmer-reported percentage lameness through risk factor analysis; and identify the population attributable fractions of these management practices. In 2014, the 5 P P was launched to provide a practical, farm-level framework to help farmers reduce lameness to reach Farm Animal Welfare Committee (FAWC) targets. No published studies have explicitly explored its uptake in UK flocks nor its association with lameness prevalence. Understanding what parts of the 5 P P farmers adopt and which elements contribute towards the greatest reduction in lameness are integral in informing future strategies. Between November 2018 and February 2019, 532 UK sheep farmers completed a cross-sectional online and paper-based survey. The geometric mean of farmer-reported percentage lameness in ewes was 3.2 % (95 % CI: 2.8-3.6). Farmers adopted a median of 3 points of the plan, but was only fully-adopted by 5.8 % of farmers. The number of points adopted increased with flock size, with larger commercial flocks more likely to cull and vaccinate against footrot, but smaller, pedigree flocks were more likely to treat individual lame sheep. Vaccination was poorly associated with the uptake of other points of the 5 P P. Eight flock management factors were associated with significantly higher percentage lameness in ewes; not carrying out measures to avoid lameness transmission, not quarantining bought in stock, not treating individual lame sheep within three days, maintaining an open flock and foot trimming were all associated with a higher risk of lameness in flocks studied. In addition, using Footvax® for ≤5 years was associated with a higher risk of lameness, although vaccination could be a consequence of high flock lameness or these farmers were not implementing other effective managements, such as treating promptly. The highest PAFs were calculated for trimming lame sheep (16.9 %), maintaining an open flock (13.5 %) and not carrying out measures to avoid lameness transmission (11.8 %). We provide new evidence documenting the benefits of adopting parts of the 5 P P on reducing lameness prevalence in UK flocks, although uptake of these measures could be improved in flocks. Encouraging uptake of these measures could make an important contribution towards reducing the prevalence of lameness and reaching 2021 FAWC ≤ 2% lameness prevalence targets.