Identification and determination of the antimicrobial susceptibility of the main respiratory pathogens isolated from calves in dairy herds with respiratory diseases in Quebec

Abstract

Bovine respiratory disease (BRD) represents 1 of the 2 most important causes of morbidity and death in dairy calves. The detrimental effects of BRD in calves on dairy herds can be substantial and includes decreased profitability because of cost of treatments, decreased growth rate, increased risk of culling before first calving, and death. Calf enzootic pneumonia is associated with multiple bacterial and viral pathogens. In the past 10 years, emerging and re-emerging respiratory pathogens, such as bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCV), and Mycoplasma bovis, have been identified as playing a major role in the development of BRD in dairy calves in North America. Field data regarding the prevalence of various BRD pathogens in dairy calves, particularly calves on small farms, are lacking. The objectives of this study were to identify the primary respiratory pathogens isolated from calves with BRD in Quebec dairy herds and to determine the antimicrobial susceptibility of those pathogens.