Bovine digital dermatitis in Victoria, Australia

Abstract

Aims The objectives of this study were to estimate the prevalence of digital dermatitis (DD) in Victoria, Australia, and to investigate which organisms are consistent with typical DD lesions. The prevalence and causative pathogens of DD are not clear yet in Australia and this paper is one of the first to explore these questions in this country.Methods Examination and sampling of limbs was undertaken at three knackeries in Victoria, Australia. Limbs were classified as normal (N), active DD-lesion (A), dried or chronic DD-lesion (D) or suspected case of DD (S). A total of 823 cows were examined. Six skin biopsies were taken at each knackery, from which DNA was extracted for diversity profiling. Histochemical staining of samples was performed on eight of the skin biopsies.Results DD was detected in 29.8% of all cows. The prevalence of DD was significantly higher in dairy cows (32.2%) than in beef cows (10.8%). The differential abundance of Treponema-species was significantly increased in dried lesions, compared with the normal skin biopsies. Actinobacteria, Proteobacteria, Firmicutes and Tenericutes were found to be significantly different in abundance in the DD lesions compared with normal skin biopsies. Silver staining of samples showed only mild inflammation and in two samples organisms with morphology consistent with Spirochaetes were detected. ConclusionsThe calculated prevalence indicates that DD is present in Victoria, Australia. The results of diversity profiling showed that the presence of Treponema-species was significantly different between the samples of DD lesions and normal skin.

Meta-Analysis of Bovine Digital Dermatitis Microbiota Reveals Distinct Microbial Community Structures Associated With Lesions

“…Treponema has been the most common genus implied as an etiologic agent of DD. Consistent with this study, virtually every other metagenomic study of DD observes a higher relative abundance of Treponema in most DD lesions compared to normal skin (Krull et al, 2014;Zinicola et al, 2015b;Marcatili et al, 2016;Nielsen et al, 2016;Hesseling et al, 2019). Conversely, it is not uncommon to see some healthy skin samples to also have high proportions of at least one species of Treponema (Beninger et al, 2018;Caddey et al, submitted for publication).…”

“…There is previous literature showing Fusobacterium as differentiating DD lesions from healthy skin (Sullivan et al, 2015;Nielsen et al, 2016;Moreira et al, 2018), but is suggested to have a larger role in chronic lesions due to it being more prevalent in those lesions (Hesseling et al, 2019). We did not identify Fusobacterium in any of the samples from V1V3 amplification.…”

“…Additional bacteria outside the genus Treponema likely play some role in DD pathogenesis based on their presence and abundance within DD lesions; however, the conclusions on which of these bacteria potentially are involved can vary dramatically across studies of DD microbiota. In addition to Treponema, many recent metagenomic studies associate Mycoplasma abundance with DD lesions (Krull et al, 2014;Nielsen et al, 2016;Hesseling et al, 2019). Inconsistencies most notably arise between studies when implicating other bacterial genera in DD pathogenesis.…”

Microbiome Shift, Diversity, and Overabundance of Opportunistic Pathogens in Bovine Digital Dermatitis Revealed by 16S rRNA Amplicon Sequencing

“…Many reports have attempted to elucidate the association of the microbiome of BDD towards disease development [ 11 , 13 , 14 , 15 ]. Surprisingly, for more than 20 years since it emerged as a major problem in the cattle industry in certain countries, studies on BDD have just recently started in Korea.…”

“…was established as the dominant pathogen in BDD lesions in Korea [ 16 ], but an emphasis on the plethora of bacteria that was observed is still lacking. Although the majority of studies considered that the main pathogen of BDD is Treponema spp., its polybacterial nature must also be considered in order to understand its pathogenesis [ 15 ]. Therefore, this study analyzed the diversity and phylogenetic relationship of the microbiome of BDD lesions and normal skin from the interdigital space of the cattle using 16S rRNA amplicon sequencing.…”