BRD is the result of a complex interaction of pathogens including viruses and bacterial agents. The initial insult is usually the result of viral infections such as bovine respiratory syncytial virus (BRSV) bovine herpes virus type 1 (BoHV-1), bovine parainfluenza-3 virus (BPI3V) and / or bovine viral diarrhoea virus (BVDV).
These viral infections predispose calves to secondary bacterial infections. Common pathogens associated with BRD include those mentioned above and Bovine coronavirus (BCoV), Bovine adenovirus-3 or 7 (BAV-3/7), Mannheimia haemolytica, Histophilus somni, Pasteurella multocida, Mycoplasma bovis and Streptococcus pnuemoniae, Mycoplasma dispar.
- Nasal Discharge
- Ocular Discharge
- Increased respiratory rate
- Droopy ears, dull eyes, and social isolation
- Weakened immune system giving rise to the secondary bacterial infections
- Increased morbidity and mortality
BRD is the most common and costly disease affecting beef cattle in the world. The disease manifests itself most often in calves within four weeks of weaning, when calves are often sold and moved to different farms.
This gives the disease the nickname, "Shipping Fever."
The pathogenesis of the disease is under study in the Virology Branch at AFBI Stormont.
This includes how the individual virus components interact to cause the initial disease and modify the animal’s immune system so that secondary bacterial infections occur.
New approaches to vaccine against these viruses are also being investigated.