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.

传染性绵羊指状皮炎 (CODD) 是一种严重且常见的绵羊传染性足病，也是英国和一些欧洲国家养羊业面临的重大动物福利问题。该病的病因和发病机制尚不完全清楚。在这项纵向实验研究中，CODD 在 18 只绵羊中被诱导，并且首次描述了 CODD 影响脚的临床病变发展和相关微生物学变化，从而对 CODD 的发病机制有了全新的理解。大多数 CODD 病变 (83.9%) 源于先前存在的指间皮炎 (ID) 和/或足腐病 (FR) 病变。足病的所有阶段都与五种病原体的高水平多细菌定植有关，通过定量 PCR (qPCR) 检测到：中等密螺旋体、噬菌体密螺旋体、足密螺旋体、结节双歧杆菌， 和 坏死梭杆菌. 时间定植模式显示出早期定植的趋势噬菌体， 其次是 F. necrophorum 和 D. nodosus, T. medium， 进而 T. pedis, D. nodosus与 ID 和 CODD 相比，FR 病变中的预测平均 log ₁₀基因组拷贝数显着更高，而密螺旋体 与 ID 病变相比，CODD 和 FR 病变中的物种显着更高（磷< 0.001)。用两剂 10 mg/kg 长效阿莫西林治疗受 CODD 影响的绵羊，治疗后 3 周临床治愈率为 91.7%；然而，并未对所有受 CODD 影响的足部建立细菌学治愈方法。研究发现，在受感染的鸡群中，健康的脚、治愈的 CODD 脚和治疗后的 CODD 脚可能被与 CODD 相关的五种病原体中的部分或全部定植，因此可能成为鸡群持续感染的来源。该研究是一项实验研究，结果需要在现场 CODD 案例中进行验证。然而，它确实为 CODD 的发病机制提供了新的理解，并进一步支持了当前关于控制 CODD 建议的重要性的证据；即确保对鸡群进行最佳的腐烂控制，并及时隔离和有效治疗临床病例。