Bovine Foot Rot and its Microbiological Relationship with Bovine Digital Dermatitis
Date
2025-01-07
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Abstract
Bovine foot rot (BFR) and bovine digital dermatitis (BDD) are important infectious diseases that cause pain and lameness in feedlot cattle. BFR causes subcutaneous tissue necrosis and is treated using systemic antibiotics whereas BDD affects outer skin layers and is treated using topical treatments, but cases often relapse. Visual diagnosis of BFR and BDD is complicated by inconclusive cases with lesion characteristics indifferentiable as either BFR or BDD. F. necrophorum and Treponema spp. are the bacteria primarily associated with the pathogenesis of BFR and BDD, respectively. Also, several Treponema spp. are found associated with disease stages of BDD, also called M-stages, of which we investigated the active M2 and chronic M4 stages. As reported in Chapter 2, we visually diagnosed cattle as either BFR, BDD-M2, BDD-M4, inconclusive, and healthy groups. We found that the absolute quantity of seven bacterial species associated with BFR and BDD pathogenesis, namely, Fusobacterium necrophorum, Fusobacterium mortiferum, Bacteroides pyogenes, Porphyromonas levii, Treponema medium, Treponema phagedenis, and Treponema pedis, were different among biopsies, swabs, and subcutaneous samples within and between the cattle groups. We also found that routine histology was not effective in differentiating BFR and BDD. Also, a producer survey indicated that the risk factors included in our survey did not increase the odds of cattle being diagnosed with either disease. In Chapter 3, using 16S rRNA gene sequencing on DNA extracted from biopsies, we found that the groups generally had similar bacterial species present, although in different proportions, with the healthy group having the most diverse microbial taxa. . In Chapter 4, using whole genome sequencing and agar dilution assay, we found that most bacterial isolates derived from biopsies from different cattle groups contained tetracycline resistance genes as compared to penicillin and ceftiofur, and phenotypic resistance was also higher for tetracycline as compared to ceftiofur and penicillin. This thesis provides quantitative insights into the potential pathogens and risk factors responsible for BFR and BDD pathogenesis, and the in vitro activities of antibiotics used for treating these diseases, while also demonstrating the comparative effectiveness of diagnostic tools for sample collection and differential diagnosis.
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Keywords
Bacteria, Cattle, Cow, Interdigital Phlegmon, Hairy Heel Warts, Feedlots, Beef, Fusobacterium necrophorum, Treponema, Porphyromonas levii
Citation
Last name, A. (2025). Bovine foot rot and its microbiological relationship with bovine digital dermatitis (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.