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Epidemiology of Hoof-Related Lameness in Western Canadian Feedlot Cattle



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The research objectives were to: 1.) To describe the epidemiology of hoof-related lameness (HRL) in western Canadian feedlots (Chapter 2) with additional focus on digital dermatitis (DD) (Chapter 3), and 2.) To analyze risk factors, at the animal-level (Chapters 2 and 3) and feedlot-level (Chapter 3) for associations with HRL and DD, and 3.) To inform recommendations for future research on the control and prevention of HRL (Chapter 2) and DD (Chapter 3). The indi-vidual animal health data included records for 1,772,565 cattle from 28 western Canadian feed-lots (2014-2018, inclusive). The case-control study in Chapter 3 segregated those same 28 feed-lots into DD case (n = 14) or DD control feedlots (n = 14), based on one or more DD cases being diagnosed (2014-2018). All data were accessed through a proprietary feedlot animal health data-base and analyzed using commercially available software. In chapter 2, lameness accounted for 28.52% of disease diagnoses, 71.80% of which were HRL cases, representing 20.64% of disease diagnoses. The incidence risk of first lifetime HRL diagnoses ranged from 1.94% to 3.07% of the population, annually. The HRL diseases focused on were foot rot (FR); DD; and toe tip necrosis syndrome (TTNS), accounting for 90.40%, 7.52% and 2.08% of HRL cases, respectively. Foot rot occurred at a constant rate throughout the feeding period by days on feed (DOF), with some variability in cases coinciding with season. Less than 10% of DD occurred before 80 DOF with 90% cases occurring by 300 DOF. Over 50% of TTNS cases occurred within the first 50 DOF and coincided with seasonal feedlot popu-lation increases during the fall placement season. For the individual animal-level analysis of chapter 2, cattle placed in small capacity feedlots (SCF), regardless of age class or acquisition source, were higher risk for HRL development than cattle placed in large capacity feedlots (LCF). The largest effect was observed in ranch-direct (RD) yearlings whose HRL risk was 4.23 times (95% CI 1.48 to 12.07, P = 0.007) higher when placed in SCF versus placement in LCF. This may be related to increased pull rates in SCF due to smaller populations and increased time allotment for identifying and treating cattle, however, the identification of the risk factors driving this difference still need to be identified. For cattle from RD-sources placed in LCF and cattle from AM-sources placed in LCF, the risk of developing HRL was 2.21 (95% CI 1.23 to 4.00, P = 0.010) and 1.45 (95% CI 1.25 to 1.68, P < 0.001) times in calves higher than yearlings, respectively. Conversely, for cattle from AM-sources placed in SCF, calves were lower risk than yearlings (RR = 0.68, 95% CI 0.52 to 0.91, P = 0.008). Future research should focus on evaluating management-level differences, such as frequency of rehandling and acquisition source, between calves and yearlings and their poten-tial associations with HRL. Confined background (CB)-sourced yearlings, placed in LCF were 7.21 (95% CI 4.46 to 11.64, P < 0.001), 2.54 (95% CI 2.12 to 3.06, P < 0.001) and 1.79 (95% CI 1.13 to 2.85, P < 0.001) times higher risk for HRL development than yearling cattle placed in LCF and sourced from RD, AM and grass cattle (GC), respectively. It is speculated that high levels of commin-gling increase the likelihood of HRL introduction, and confinement in potentially poor pen con-ditions may predispose CB-sourced cattle to poor hoof integrity. Yearlings from GC-sources placed in LCF were 4.02 (95% CI 2.13 to 7.58; P < 0.001) times higher risk than RD-sourced yearlings placed in LCF. Ranch direct-sourced calves placed in LCF (RR = 0.54, 95% CI 0.37 to 0.79, P = 0.002) and RD-sourced yearlings placed in LCF (RR = 0.35, 95% CI 0.22 to 0.56, P = < 0.001) were lower risk for HRL versus their age class counterparts placed in LCF and sourced from AM, respectively. It is speculated, similarly to CB sources, that increased commingling of unknown cattle in GC and AM sources increases the likelihood of HRL introduction into the population. In Chapter 3, the RR of DD in females was 4.98 (95% CI 2.97 to 8.33, P < 0.001), 2.79, (95% CI 1.54 to 5.05, P < 0.001) and 1.85 (95% CI 1.16 to 2.95, P = 0.009) times higher than males in high morbidity (HighMorb) years, medium morbidity (MediumMorb) years, and low morbidity (LowMorb) years, respectively. Future research should focus on determining if this is a result of differences in physical characteristics, or the management of males and females. Com-pared to AM cattle, the risk of developing DD was greater in cattle sourced from CB (RR = 2.63, 95% CI 1.92 to 3.59, P < 0.0001) and GC (RR = 2.00, 95% CI 1.18 to 3.39, P = 0.010), but lower in RD (RR = 0.04, 95% CI 0.01 to 0.10, P < 0.001). It is speculated here that in-creased commingling may introduce DD into the population. Cattle placed in quarter (Qtr) 1 (RR = 1.66, 95% CI 1.06 to 2.60, P = 0.027) and cattle placed in Qtr2/Qtr3 (RR = 2.28, 95% CI 1.48 to 3.52, P < 0.001) were higher risk for DD than cattle placed in Qtr4. These results are likely due to fluctuations in pen conditions during the spring and summer months. The relative risk of DD development was lower for cattle in SCF compared to LCF (RR = 0.24, P = 0.027). At the feedlot level, SCF were at a lower risk of having a confirmed case of DD than LCF (RR = 0.24, 95% CI = 0.05 to 0.76 P = 0.027). For both results, it is speculated that LCF acquire cattle from a wider variety of sources than SCF. This increased variation in sources reflects an increase in commingling of unknown cattle and increased potential for novel diseases, such as DD, to be introduced into the population. Acquisition source, sex, and age class at the animal-level, as well as feedlot population size, both at the animal and feedlot level, play important roles in the development and incidence risk of HRL and DD in western Canadian feedlots. Additional research is recommended to broaden the knowledge base concerning HRL and DD, and to provide insights regarding management tools for the control and prevention of lameness in feedlots.



Epidemiology, Feedlot Cattle, Hoof-Related Lameness, Digital Dermatitis



Master of Science (M.Sc.)


Large Animal Clinical Sciences


Large Animal Clinical Sciences


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