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.

This open-label, randomized clinical trial with positive control compared the treatment of active digital dermatitis (DD) lesions (stages M1, M2, and M4.1) on dairy cattle hind feet with an enzyme alginogel or a copper and zinc chelate gel (coppergel). Upon recruitment (d 0), active DD lesions were cleaned, photographed, treated, and bandaged. This procedure was repeated on d 3 and d 7, with treatment and bandaging discontinued for those lesions that had transitioned to the M0, M3, or M4 stage on d 7. Day 10 was considered the end of the treatment trial, and all recruited feet were cleaned and photographed. Treatment effect of the 2 products was assessed not only using the M-score but also using general wound healing progress criteria. Improvement of M-score was defined as transition to M0, M3, or M4 stages, or to lesions with a smaller ulcerative area (e.g., M2 stage to M1 stage). Lesions with improved wound healing had at least one of the following criteria when compared with the previous observation: decreased defect size, healthier granulation tissue color (pinkred instead of purple-grayish), more regular aspect of granulation tissue surface, wound contraction, or epithelization starting from the surrounding skin. Both primary outcomes were assessed using a multivariable logistic regression analysis. Lesions treated with the enzyme alginogel had a decreased adjusted odds ratio for M-score improvement (aOR: 0.04; 95% confidence interval: 0.01-0.11). Lesions treated with the coppergel mostly transitioned to chronic lesions, whereas lesions treated with the enzyme alginogel mostly remained active lesions. The wound healing progress of almost 70% of the lesions treated with coppergel could not be scored, for the greater part due to the presence of crust materials. With these unscorable lesions classified as "improved," there was no treatment effect on wound healing progress (aOR: 0.99; 95% confidence interval: 0.34-3.05), whereas with unscorable lesions classified as "not improved," the enzyme alginogel outperformed the coppergel with regard to wound healing progress (aOR: 2.48; 95% confidence interval: 1.07-5.79). None of the products used in our study achieved high cure rates (transition to the M0 stage) for active DD lesions. Low cure rates of topical treatment of DD, together with the important role of chronic lesions in the epidemiology of DD, indicate that future research should investigate how to achieve successful wound management of DD lesions, thereby mitigating pain associated with the lesions and reducing both transmission and prevalence of DD within herds.