Bovine respiratory disease (BRD) — commonly called "shipping fever" in North America or "pneumonia" in the UK — is the most economically and welfare-significant disease complex affecting beef and dairy cattle worldwide. It accounts for the majority of morbidity and mortality in weaned calves and is the leading cause of antibiotic use in cattle production.
Pathogenesis
BRD is a multifactorial disease requiring the interaction of:
- Viral pathogens: Bovine herpesvirus type 1 (IBR), bovine coronavirus (BCoV), bovine respiratory syncytial virus (BRSV), bovine viral diarrhoea virus (BVD) — viruses impair mucociliary clearance and macrophage function, opening the respiratory tract to bacterial secondary infection
- Bacterial pathogens: Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Mycoplasma bovis — cause the pneumonic lesions responsible for morbidity and mortality
- Host stress: Weaning, transport, mixing, dietary change, and weather extremes suppress immune function and amplify susceptibility
Clinical Signs and Early Detection
Early detection is critical — treatment response rates decline sharply as disease progresses. Key early signs include:
- Separation from group — sick animals stand apart
- Nasal discharge (initially clear, progressing to mucopurulent)
- Coughing and increased respiratory effort
- Elevated rectal temperature (>39.5°C — use thermometer routinely in at-risk animals)
- Reduced appetite and dull demeanour
- Watery or sunken eyes
Prevention Strategies
Vaccination: IBR, BVD, BCoV, and BRSV vaccines should be included in respiratory disease prevention programmes — timing relative to risk events (weaning, purchase) is critical for vaccine-induced protection to develop before challenge.
Metaphylaxis: Antibiotic treatment of entire high-risk groups at arrival (e.g., purchased weaned calves) prevents early BRD deaths but raises antimicrobial resistance concerns — should be used selectively based on risk assessment.
Management: Gradual weaning, minimising transport duration and mixing of unknown-health-status animals, ensuring adequate nutrition and water at arrival, and providing shelter all reduce BRD risk.
Treatment
Antibiotic therapy (tulathromycin, florfenicol, enrofloxacin — based on sensitivity patterns) alongside NSAIDs (meloxicam, flunixin) for fever and inflammation control. NSAID treatment alone without antibiotics is inadequate for bacterial BRD. Supportive care (electrolytes, vitamin C supplementation) assists recovery in severe cases.
Welfare Significance
BRD causes significant acute suffering — high fever, dyspnoea, and systemic illness are painful. Chronic survivors may have lasting lung damage (adhesions, consolidation) affecting lifetime performance and welfare. Investment in prevention through vaccination, management, and housing improvement reduces both the scale of suffering and the economic costs of treatment and mortality.