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Bhardwaj V, Dhungyel OP, de Silva K, Dhand NK, Whittington RJ. The role of foot conformation in susceptibility of Merino sheep to footrot. Small Rumin Res 2022. [DOI: 10.1016/j.smallrumres.2022.106850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Clifton R, Monaghan EM, Green MJ, Purdy KJ, Green LE. Differences in composition of interdigital skin microbiota predict sheep and feet that develop footrot. Sci Rep 2022; 12:8931. [PMID: 35624131 PMCID: PMC9142565 DOI: 10.1038/s41598-022-12772-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 05/12/2022] [Indexed: 11/29/2022] Open
Abstract
Footrot has a major impact on health and productivity of sheep worldwide. The current paradigm for footrot pathogenesis is that physical damage to the interdigital skin (IDS) facilitates invasion of the essential pathogen Dichelobacter nodosus. The composition of the IDS microbiota is different in healthy and diseased feet, so an alternative hypothesis is that changes in the IDS microbiota facilitate footrot. We investigated the composition and diversity of the IDS microbiota of ten sheep, five that did develop footrot and five that did not (healthy) at weekly intervals for 20 weeks. The IDS microbiota was less diverse on sheep 2 + weeks before they developed footrot than on healthy sheep. This change could be explained by only seven of > 2000 bacterial taxa detected. The incubation period of footrot is 8–10 days, and there was a further reduction in microbial diversity on feet that developed footrot in that incubation period. We conclude that there are two stages of dysbiosis in footrot: the first predisposes sheep to footrot and the second occurs in feet during the incubation of footrot. These findings represent a step change in our understanding of the role of the IDS microbiota in footrot pathogenesis.
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Affiliation(s)
- Rachel Clifton
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, UK.
| | - Emma M Monaghan
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, UK
| | - Martin J Green
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Leicestershire, UK
| | - Kevin J Purdy
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Laura E Green
- Institute of Microbiology and Infection, University of Birmingham, Edgbaston, UK
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Staton GJ, Angell JW, Grove-White D, Clegg SR, Carter SD, Evans NJ, Duncan JS. Contagious Ovine Digital Dermatitis: A Novel Bacterial Etiology and Lesion Pathogenesis. Front Vet Sci 2021; 8:722461. [PMID: 34631855 PMCID: PMC8496452 DOI: 10.3389/fvets.2021.722461] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/10/2021] [Indexed: 12/12/2022] Open
Abstract
Contagious ovine digital dermatitis (CODD) is a severe and common infectious foot disease of sheep and a significant animal welfare issue for the sheep industry in the UK and some European countries. The etiology and pathogenesis of the disease are incompletely understood. In this longitudinal, experimental study, CODD was induced in 18 sheep, and for the first time, the clinical lesion development and associated microbiological changes in CODD affected feet are described over time, resulting in a completely new understanding of the etiopathogenesis of CODD. The majority of CODD lesions (83.9%) arose from pre-existing interdigital dermatitis (ID) and/or footrot (FR) lesions. All stages of foot disease were associated with high levels of poly-bacterial colonization with five pathogens, which were detected by quantitative PCR (qPCR): Treponema medium, Treponema phagedenis, Treponema pedis, Dichelobacter nodosus, and Fusobacterium necrophorum. Temporal colonization patterns showed a trend for early colonization by T. phagedenis, followed by F. necrophorum and D. nodosus, T. medium, and then T. pedis, D. nodosus was present at significantly higher predicted mean log10 genome copy numbers in FR lesions compared to both ID and CODD, while Treponema species were significantly higher in CODD and FR lesions compared to ID lesions (p < 0.001). Treatment of CODD-affected sheep with two doses of 10 mg/kg long acting amoxicillin resulted in a 91.7% clinical cure rate by 3 weeks post-treatment; however, a bacteriological cure was not established for all CODD-affected feet. The study found that in an infected flock, healthy feet, healed CODD feet, and treated CODD feet can be colonized by some or all of the five pathogens associated with CODD and therefore could be a source of continued infection in flocks. The study is an experimental study, and the findings require validation in field CODD cases. However, it does provide a new understanding of the etiopathogenesis of CODD and further supportive evidence for the importance of current advice on the control of CODD; namely, ensuring optimum flock control of footrot and prompt isolation and effective treatment of clinical cases.
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Affiliation(s)
- Gareth J Staton
- Department of Infection Biology & Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, The University of Liverpool, Neston, United Kingdom
| | - Joseph W Angell
- Department of Infection Biology & Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, The University of Liverpool, Neston, United Kingdom.,Wern Vets CYF, Department of Research and Innovation, Unit 11, Lon Parcwr Industrial Estate, Ruthin, United Kingdom
| | - Dai Grove-White
- Department of Livestock and One Health, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Neston, United Kingdom
| | - Simon R Clegg
- Department of Infection Biology & Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, The University of Liverpool, Neston, United Kingdom.,School of Life Sciences, College of Science, University of Lincoln, Lincoln, United Kingdom
| | - Stuart D Carter
- Department of Infection Biology & Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, The University of Liverpool, Neston, United Kingdom
| | - Nicholas J Evans
- Department of Infection Biology & Microbiomes, Institute of Infection, Veterinary and Ecological Sciences, The University of Liverpool, Neston, United Kingdom
| | - Jennifer S Duncan
- Department of Livestock and One Health, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Neston, United Kingdom
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Smith KJ, Rosser MJ, McPherson AS, Whittington RJ, Dhand NK, Dhungyel OP. The severity of footrot lesions induced by aprV2-positive strains of Dichelobacter nodosus varies between strains. Aust Vet J 2021; 99:279-287. [PMID: 33778952 DOI: 10.1111/avj.13065] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/25/2021] [Accepted: 03/07/2021] [Indexed: 12/30/2022]
Abstract
OBJECTIVES The primary objective of this study was to evaluate the clinical virulence of aprV2-positive lesser virulent field isolates of footrot bacteria Dichelobacter nodosus in comparison with an aprV2-positive clinically virulent reference strain. Correlations between the clinical expression of the disease and the presence of aprV2 (detected using PCR tests) have been inconsistent. A second objective was to evaluate the elimination of D. nodosus following treatment of sheep as some strains of D. nodosus have been reported to be difficult to eliminate. METHODS The virulence of three aprV2-positive field isolates of D. nodosus which had lesser virulent phenotypes, and an aprV2-positive virulent reference strain was evaluated in a sheep trial using a pasture-based experimental infection model. In the second phase of the study, treatments including footbathing and a long-acting antibiotic were administered and their efficacy in elimination of these strains was evaluated. RESULTS Severe underrun (score 4) lesions developed in sheep infected with the aprV2-positive virulent reference strain but not in sheep infected with the field isolates; they had mild lesions (score 2 or 3). The three field isolates and the virulent reference strain of D. nodosus were eliminated by intensive foot bathing and antibiotic therapy in combination with housing the animals in dry conditions post-treatment. CONCLUSION The results suggest that the presence of aprV2 gene in isolates of D. nodosus may not be a reliable indicator of virulence and that further investigation of the factors that determine clinical virulence is required. While the treatment regime was successful, based on a range of considerations, the use of such an intensive treatment involving antibiotics should be limited to small groups of high-value animals, such as rams.
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Affiliation(s)
- K J Smith
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - M J Rosser
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - A S McPherson
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - R J Whittington
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - N K Dhand
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
| | - O P Dhungyel
- Farm Animal Health, Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, 425 Werombi Road, Camden, New South Wales, 2570, Australia
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Characterisation of Dichelobacter nodosus on Misshapen and Damaged Ovine Feet: A Longitudinal Study of Four UK Sheep Flocks. Animals (Basel) 2021; 11:ani11051312. [PMID: 34063612 PMCID: PMC8147629 DOI: 10.3390/ani11051312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 04/27/2021] [Accepted: 04/30/2021] [Indexed: 12/15/2022] Open
Abstract
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.
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