The presented scoping review summarizes the available research evidence and identifies gaps in knowledge for bovine respiratory disease (BRD) prevention. Published literature on BRD from 1990 to April 2021 was searched in online databases, including Medline, CAB Abstracts, Scopus, Biosis, and Searchable Proceedings of Animal Conferences. Citations were systematically evaluated in a three-stage approach using commercial software and summarized in a scoping review format. A total of 265 publications were included in this review with herd/farm management (27.9%) as the most prevalent factors studied, followed by metaphylaxis (24.5%), vaccinations (24.1%), diet formulations, and nutritional supplementations (17.7%), animal characteristics (10.2%), and less common interventions and risk factors (6.4%). A high proportion of studies under herd/farm management (73%), metaphylaxis (86%), vaccinations (70%), animal characteristics (78%), and less common interventions and risk factors (59%) showed either significant effects on reducing BRD morbidity or significant differences of BRD between treatments. However, diet and nutritional supplementations reduced BRD only in 30% of research publications. Most studies on BRD were performed in feedlot populations, and more studies in cow-calf populations are needed. We further suggest meta-analyses on the use of yeast and trace mineral supplementation, and nitric oxide-releasing solution for BRD prevention.

Diagnosis of bovine respiratory disease (BRD) in beef cattle placed in feedlots is typically based on clinical illness (CI) detected by pen-checkers. Unfortunately, the accuracy of this diagnostic approach (namely, sensitivity [Se] and specificity [Sp]) remains poorly understood, in part due to the absence of a reference test for ante-mortem diagnosis of BRD. Our objective was to pool available estimates of CI\'s diagnostic accuracy for BRD diagnosis in feedlot beef cattle while adjusting for the inaccuracy in the reference test. The presence of lung lesions (LU) at slaughter was used as the reference test. A systematic review of the literature was conducted to identify research articles comparing CI detected by pen-checkers during the feeding period to LU at slaughter. A hierarchical Bayesian latent-class meta-analysis was used to model test accuracy. This approach accounted for imperfections of both tests as well as the within and between study variability in the accuracy of CI. Furthermore, it also predicted the SeCI and SpCI for future studies. Conditional independence between CI and LU was assumed, as these two tests are not based on similar biological principles. Seven studies were included in the meta-analysis. Estimated pooled SeCI and SpCI were 0.27 (95% Bayesian credible interval: 0.12-0.65) and 0.92 (0.72-0.98), respectively, whereas estimated pooled SeLU and SpLU were 0.91 (0.82-0.99) and 0.67 (0.64-0.79). Predicted SeCI and SpCI for future studies were 0.27 (0.01-0.96) and 0.92 (0.14-1.00), respectively. The wide credible intervals around predicted SeCI and SpCI estimates indicated considerable heterogeneity among studies, which suggests that pooled SeCI and SpCI are not generalizable to individual studies. In conclusion, CI appeared to have poor Se but high Sp for BRD diagnosis in feedlots. Furthermore, considerable heterogeneity among studies highlighted an urgent need to standardize BRD diagnosis in feedlots.