In veterinary circles, we sometimes think of BRD management as a triad with three points of influence — the pathogen, the animal and husbandry practices. Understanding each point can help veterinarians and producers focus on the essential elements (i.e., trigger points) that may contribute to BRD, possibly leading to prevention or early detection/treatment.
When it comes to disease, understanding the pathogen point of the triad is key. BRD is associated with several viral and bacterial pathogens that can act alone or together to cause disease. The most common include Mannheimia haemolytica, Pasturella multocida, Histophilus somni and Mycoplasma bovis.1
The pathogenesis (manner of development) of BRD can involve many factors. Stress as well as viral or parasitic infections can suppress the immune system, which can then allow bacteria to rapidly reproduce in the upper respiratory tract.