Investigating the Polymicrobial Nature of Bovine Digital Dermatitis in Natural Infections and Animal Models

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dc.contributor.advisorDe Buck, Jeroen
dc.contributor.authorPetersen Dias, Angelica
dc.contributor.committeememberOrsel, Karin
dc.contributor.committeememberCobo, Eduardo
dc.contributor.committeememberMorck, Douglas Walter
dc.contributor.committeememberSycuro, Laura K.
dc.contributor.committeememberPlummer, Paul J.
dc.date2025-06
dc.date.accessioned2024-12-18T19:49:04Z
dc.date.available2024-12-18T19:49:04Z
dc.date.issued2024-12-12
dc.description.abstractDigital Dermatitis (DD) is a multifactorial, polymicrobial skin disease on cattleā€™s feet and is the leading cause of lameness in Canadian dairy cattle, with an etiology that remains unclear. This thesis aimed to investigate the polymicrobial nature of DD by identifying potential bacterial reservoirs and investigating the roles of specific bacteria in lesion initiation in natural infections. Additionally, efforts were made to optimize a bovine infection model. Four studies were conducted, three field studies in commercial dairy farms and an experimental infection study. We relied on quantitative molecular techniques, real-time qPCR, targeting three DD-associated Treponema spp. and four other anaerobes. First, we validated swabs as an alternative to invasive skin biopsies in detecting and quantifying DD bacteria. We then mapped and quantified DD bacteria in potential reservoirs in dairy cows from herds with or without DD. Next, we assessed the temporal changes in bacterial counts preceding lesions and determined whether bacterial presence in reservoirs was persistent or transient in a longitudinal study. Finally, we explored a novel tattoo-based inoculation method to optimize DD bovine models. DD-Treponema spp. were detected only in DD-affected herds, while non-treponemal anaerobes were widespread in both affected and DD-negative herds. Although all target bacterial species were occasionally detected on healthy skin and in saliva, only Porphyromonas levii and Fusobacterium necrophorum seem to persist in these sites. Despite their detection in environmental samples, we did not detect any of the target species in feces. All target species increased in numbers before lesion onset, with sequential colonization starting with non-treponemes two weeks before DD occurred, followed by DD-Treponema spp. Lastly, the tattooing method showed potential for future use in experimental induction of DD by depositing Treponema spp. at the epidermis-dermis junction; however, we were unable to induce lesions in dairy calves likely due to factors missing in our model. While DD etiology remains undetermined, this thesis supports the key role of Treponema spp. in the disease, offers a change in perspective on the involvement of non-treponemes in lesion initiation, discusses the challenges in reproducing this disease experimentally, and proposes a hypothetical scheme of pathogenesis for this complex disease.
dc.identifier.citationPetersen Dias, A. (2024). Investigating the polymicrobial nature of bovine digital dermatitis in natural infections and animal models (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.urihttps://hdl.handle.net/1880/120217
dc.language.isoen
dc.publisher.facultyGraduate Studies
dc.publisher.institutionUniversity of Calgary
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subjectDairy cattle
dc.subjectHoof infectious disease
dc.subjectLameness
dc.subjectTreponema
dc.subjectPorphyromonas
dc.subjectFusobacterium
dc.subjectReal-time qPCR
dc.subject.classificationVeterinary Science
dc.subject.classificationMicrobiology
dc.titleInvestigating the Polymicrobial Nature of Bovine Digital Dermatitis in Natural Infections and Animal Models
dc.typedoctoral thesis
thesis.degree.disciplineVeterinary Medical Sciences
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.thesis.accesssetbystudentI do not require a thesis withhold ā€“ my thesis will have open access and can be viewed and downloaded publicly as soon as possible.
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