Footrot is a contagious disease of sheep and other small ruminants. The causative agent, Dichelobacter nodosus, is transmitted between hooves via contaminated pasture and soil. However, the bacterium cannot invade the epidermis unless it is compromised in some manner and water maceration, which follows prolonged exposure to a moist substrate, is the most common predisposing factor. Experimental infection models have been used extensively to study the aetiology, pathogenesis, treatment and prevention of footrot. In Australia, an indoor, pen-based, infection model involving standing sheep on wet mats and bandaging inoculum onto the foot has been used commonly but does not accurately represent the pasture environment and has an impact on animal welfare. Instead, we predisposed sheep on irrigated pasture and compared three methods for infecting them with D. nodosus: application of inoculum to the interdigital skin with a swab, dripping inoculum onto the interdigital skin with a pipette, and spraying inoculum onto the pasture on which the sheep grazed. We were able to establish D. nodosus infections using all three methods but selected the swab method for further use because the dose can be controlled. It was used in two field trials and infection was established in 70% to 100% of sheep. The infection model developed in this study improves animal welfare by reducing the level of intervention. However, as the model is pasture-based, seasonal weather patterns need to be considered to ensure predisposition and disease expression. Further research will be required to understand the environmental conditions required for transmission of D. nodosus and the clinical expression of disease.

脚腐病是绵羊和其他反刍动物的传染性疾病。病原体结节杆菌通过污染的牧场和土壤在蹄之间传播。但是，除非细菌以某种方式受到损害，否则细菌无法侵入表皮，而长时间暴露于潮湿的底物后浸水是最常见的诱发因素。实验性感染模型已被广泛用于研究足癣的病因，发病机理，治疗和预防。在澳大利亚，通常使用室内笔型感染模型，该模型包括将绵羊放在湿垫上并将接种物包扎到脚上，但不能准确地代表牧场环境，并且会影响动物福利。取而代之的是，我们将绵羊置于灌溉牧场上，并比较了三种感染野菜毛虫的方法：用棉签将接种物涂在指间皮肤上，用移液管将接种物滴到指间皮肤上，再将接种物喷洒到绵羊放牧的牧场上。我们能够使用所有三种方法建立诺氏梭菌感染，但选择了拭子方法以进一步使用，因为剂量可以控制。它在两次田间试验中都使用过，在70％到100％的绵羊中已经确定了感染。本研究开发的感染模型通过降低干预水平来改善动物福利。但是，由于该模型基于牧场，因此需要考虑季节性天气模式以确保易感性和疾病表达。需要进一步的研究以了解诺氏梭菌传播所需的环境条件 以及疾病的临床表现。