What is Bovine Respiratory Disease?

The Bovine Respiratory Disease Complex (BRD) groups together different diseases affecting the respiratory system of cattle, such as bronchopneumonia. It is commonly referred to as shipping fever in feedlot cattle or enzootic calf pneumonia in young dairy calves.

BRD is the most common and costly disease complex in North American Beef and Dairy Cattle^(1,2).
Several factors contribute to BRD, some of which are of particular importance:
      - Animal: age, anatomy, source, and immune status
      - Management: handling, housing conditions, vaccination status, biosecurity measures
      - Microbes: multiple bacterial and viral agents are involved

BRD is commonly associated with immunosuppressive situations caused by stressful factors such as transporting, loading, and commingling of cattle.

Mannheimia haemolytica

Gram negative bacteria, an organism frequently found in the normal respiratory tract of ruminants with overgrowth causing severe lesions of the pulmonary parenchyma.

Pasteurelia multocida

Gram negative bacteria and commensal organism found in the deep pharyngeal region, especially in young calves, inducing lung inflammation.

Histophilus somni

Gram negative bacteria and commensal organism of the nasopharyngeal region and lower respiratory tract, producing histamine which may explain early respiratory damage.

Mycoplasma bovis

Anaerobic bacteria of the deep respiratory tract, causing the lipid peroxidation of the host cell wall, and responsible for the phenotypic variation allowing evasion of the immune responses of the host.

BHV-1 (IBR)

Bovine Herpesvirus Type 1 (BHV-1) or Infectious Bovine Rhinotracheitis (IBR) as it is commonly known, initially infects the epithelial cells of the upper respiratory tract, then spreads to the lower respiratory tract and induces immunosuppression. The IBR virus causes permanent infections.

PI3

Bovine Parainfluenza virus type 3 (PI3), together with other pathogens,  forms the complex of enzootic pneumonia and causes primary infections in the epithelial cells of the trachea, bronchi and alveoli, causing necrosis of the ciliated epithelium and leading to mucociliary erosion.  This  predisposes the lung tissue to secondary bacterial infections.

BRSV

Bovine respiratory syncytial virus (BRSV) can be considered a primary pathogen of BRD. The primary infection begins in the nasal cavity, pharynx, trachea, bronchi and bronchial epithelial cells. It induces cilia loss or necrosis of bronchial and bronchiolar epithelial cells, providing an ideal environment for bacterial colonization. Ultimately, severe BRSV infection can result in subcutaneous emphysema.

BVDV

Bovine Viral Diarrheal (BVD) virus destroys alveolar macrophages inducing immunosuppression, and is associated with a wide spectrum of disease.

Respiratory Coronavirus

Bovine respiratory coronavirus contributes with other agents to enzootic calf pneumonia or shipping fever.

The simultaneous management of several risk factors is critical to properly deal with preventive and therapeutic approaches of BRD.

Inherent risks:

Sex, Age, Weight at arrival, Immune system status, Operating procedures, Quarantine & Acclimation process, Vaccination

Balanced ration:

Mineral and vitamin supplementation

Farm structure:

Space at the feed bunk, Pen design, Cooling system

Nutritional management:

Balance ration, Mineral and vitamin supplementation

Symptoms usually develop within 4 weeks after weaning / shipment in beef calves and can range from mild to severe.³

• Fever
• Depression
• Increased respiratory rate
• Cough 
• Nasal discharge