Bovine digital dermatitis in Victoria, Australia

Bovine digital dermatitis (DD) is a contagious disease and an important cause of lameness in cattle worldwide. Treponema-species are likely to be the primary pathogens of DD, however, it is considered that DD is a polymicrobial disease for which the causative pathogens are not fully understood. The causative pathogens of DD are not clear yet in Australia and this information is important to aid in the development of education, treatment methods and preventive measures. A total of 18 skin biopsies were taken on three different knackeries in Victoria, Australia, which consisted of two biopsies from normal skin, two biopsies from active lesions and two biopsies from dried lesions (for each knackery). DNA extraction and amplification from the biopsies was performed and 16S rRNA diversity profiling was completed. The diversity profiling showed no clear clustering between active, dried and normal skin biopsies. Two biopsies of normal, healthy skin tissues were positive for Treponema-species, and of dried and active lesions 5 out of 12 biopsies were positive for Treponema. There was no significant difference in the presence of Treponema between the three sample groups. Since the presence of Treponema was not limited to samples from animals with DD-like lesions, and considering the similarity of microbial compositions in samples (as compared with other studies), the results of this study might suggest that the aetiology of DD in Australia is different from the aetiology of DD in other countries.