Browsing by Author "Caddey, Benjamin"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    An experimental model to induce digital dermatitis in beef calves
    (2022-06-23) Thomas, Anice D.; Pajor, Edmond A.; Caddey, Benjamin; Goldhawk, Christy; Martins, Larissa; Orsel, Karin
    Abstract Background Digital dermatitis (DD) is a multifactorial infectious disease affecting the skin on feet of cattle causing erosion and inflammation above the heel bulbs. Some cases of DD cause lameness and significantly impact animal welfare and productivity. While DD has emerged as a concern for the beef industry, key information regarding early detection and its impact on cattle behaviour is lacking. The primary objective of this study was to determine if an established DD experimental model for dairy calves could be used to induce DD lesions in beef calves. A secondary objective was to describe changes in behaviour and pain associated with induction of DD lesions. Eight beef calves acquired from a single cow-calf operator were enrolled in the study. Upon enrolment, calves were evaluated and determined to be free of foot lesions. Within the experimental environment, calves were housed in individual pens and assigned to two groups (mock-inoculated and inoculated). Both hind feet of each calf were enrolled. Within calf, inoculation protocol was consistent, and a 28-day experimental protocol was employed. Two days prior to inoculation, both hind feet of each calf were abraded (area above the heel bulbs and below the dewclaws), moistened, and wrapped to facilitate an anaerobic condition. Feet were inoculated with macerated DD lesion material or mock inoculum and remained wrapped until clinical signs of DD or protocol endpoint. Results After a period of 14 to 18 days post inoculation, three of five inoculated calves developed clinical signs (lameness), and upon close inspection, DD lesions were present on at least one hind foot. Two of five inoculated calves did not develop lesions within 28 days. Zero of three mock-inoculated calves developed DD. Treponema spp. were detected by quantitative polymerase chain reaction from biopsies of induced lesions. Measurements of behaviour prior to disease induction were numerically different between DD affected and mock-inoculated calves. Conclusions An experimental infection model established for dairy cattle was used to successfully induce acute DD lesions in three of five inoculated beef calves. This model can provide a framework to study intervention protocols and to evaluate the impact of DD on behaviour and pain.
  • Thumbnail Image
    ItemOpen Access
    Characterizing the microbiota of bovine digital dermatitis
    (2021-03-24) Caddey, Benjamin; De Buck, Jeroen; Orsel, Karin; Morck, Douglas
    Bovine digital dermatitis (DD) is a skin disease affecting cattle worldwide. As a significant contributor to infectious lameness, DD is increasingly an economic and animal welfare concern for dairy and beef producers. DD is a polymicrobial disease, with many different types of anaerobic bacteria strongly associated with lesions. No causative agents or etiopathogenesis mechanisms of DD are yet accepted due to the multiple different species present and microbiota variation among individual lesions. The involvement of Treponema in lesion development is generally accepted, whereas what combination of other anaerobic bacteria are involved is currently debated. Insufficient and incomplete identification and characterization of these additional species are a limiting factor in DD pathogenesis research. This thesis aimed to fill the gaps in knowledge of these additional anaerobes throughout DD lesions, while providing the first comprehensive description of DD microbiota in feedlot beef cattle. Through high throughput sequencing and culturing of DD tissue biopsies, we identified Treponema, Mycoplasma, Fusobacterium spp., Porphyromas levii, and Bacteroides pyogenes as potential DD pathogens, and used a multiplex qPCR for absolute quantification and reproducible characterization of species population dynamics. We identified T. medium, P. levii, and T. phagedenis as a group strongly associated with early lesion stages, thus potentially being involved in lesion formation. Through a meta-analysis of all publicly available DD metagenomic studies, we identify Treponema, Mycoplasma, Fusobacterium, and Porphyromonas as the primary DD-associated microbiota. We recommend focusing future DD research efforts on culturing and characterizing species of these groups in an effort to establish etiopathogenesis mechanisms of DD.