Retrospective study of the relative frequency of cattle respiratory disease pathogens in clinical laboratory samples...

The objective of this study was to explore the relative frequency and seasonality of bovine respiratory pathogens in the UK, based on clinical case submission for laboratory PCR testing.

This study used retrospective data generated by a central Scotland laboratory using 407 clinical (pooled) samples collected by 95 veterinary practices located throughout the UK between November 2020 and September 2022. Statistical analyses were performed using descriptive spatial analysis (choropleth maps), chi-squared analysis, Poisson and logistic regression modelling.

The majority (77.6%) of the samples had more than one species of bacteria identified, and 17.7% had multiple viruses identified. In comparison with the colder months of autumn and winter (September to February), the warmer months (March to August) were significantly associated with lower odds of respiratory disease caused by certain pathogens. Poisson models showed small but significant univariable associations between total viruses (coefficient = ‒0.01, standard error [SE] = 0.004, 95% confidence interval [CI] = ‒0.02 to ‒0.003) and total pathogens (coefficient = ‒0.005, SE = 0.002, 95% CI = ‒0.008 to 0.002) and increasing weekly age.

This is an inherently biased population because it only comprises clinical samples submitted to a single UK laboratory, and the data were analysed retrospectively.

A large majority of clinical bovine respiratory disease (BRD) samples were multipathogenic, and pathogens such as bovine coronavirus (which has generally not been considered a significant contributing pathogen in the BRD complex in the UK) were prevalent.