What is bovine respiratory disease (BRD)?
Bovine respiratory disease (BRD) is a common and costly disease complex that affects the respiratory tract of cattle. It is caused by a combination of stress, viruses, bacteria, and environmental conditions that weaken the immune system and allow respiratory infections to develop.
BRD is one of the leading causes of illness and death in calves and young cattle in the United States.
What causes BRD?
BRD is usually caused by several factors occurring together rather than a single infection.
Common viral pathogens involved in BRD include:
- Infectious bovine rhinotracheitis (IBR)
- Bovine viral diarrhea virus (BVDV)
- Bovine respiratory syncytial virus (BRSV)
- Parainfluenza virus type 3 (PI3)
Common bacterial pathogens include:
- Mannheimia haemolytica
- Pasteurella multocida
- Histophilus somni
- Mycoplasma bovis
Stressors such as weaning, transportation, overcrowding, weather changes, poor ventilation, or mixing groups of cattle often increase the risk of disease.
Which cattle are most at risk?
Young calves are especially vulnerable because their immune systems are still developing.
Risk factors for BRD include:
- Failure of adequate colostrum intake
- Poor ventilation
- Overcrowding
- Nutritional deficiencies
- Sudden weather changes
- Weaning stress
- Transportation stress
- Concurrent illness
- Poor bedding or sanitation
Calves that develop respiratory disease early in life may have reduced growth, delayed breeding age, lower future milk production, and a higher risk of death or culling.
What are the signs of BRD?
Signs of BRD can range from mild to severe.
Common symptoms include:
- Fever
- Nasal discharge
- Coughing
- Rapid breathing
- Difficulty breathing
- Reduced appetite
- Lethargy
- Depression
- Increased lung sounds
- Weight loss
Severe cases can result in pneumonia or death.
How is BRD diagnosed?
Diagnosis is usually based on:
- Clinical signs
- Physical examination
- Rectal temperature
- Lung auscultation
- Herd history and management conditions
In some cases, veterinarians may recommend additional testing such as:
- Nasal swabs
- Tracheal washes
- Ultrasound
- Bloodwork
- Necropsy and laboratory testing
How is BRD treated?
Treatment often includes:
- Antibiotics for bacterial infections
- Anti-inflammatory medications
- Fluids and supportive care
- Reducing stress
- Improving ventilation and housing conditions
Early detection and treatment improve the likelihood of recovery.
Can BRD be prevented?
Many cases of BRD can be reduced through good management and vaccination programs.
Important prevention strategies include:
- Providing high-quality colostrum shortly after birth
- Maintaining clean, dry bedding
- Improving ventilation
- Avoiding overcrowding
- Minimizing stress during weaning and transport
- Proper nutrition
- Following a veterinarian-designed vaccination program
Are vaccines effective against BRD?
Vaccines can help reduce the severity of disease, illness, and death associated with BRD, but they do not completely eliminate risk.
Most dairy vaccination programs focus on protecting cattle against the major viral causes of BRD, including:
- Infectious bovine rhinotracheitis (IBR)
- Bovine viral diarrhea virus (BVDV)
- Bovine respiratory syncytial virus (BRSV)
- Parainfluenza virus type 3 (PI3)
Research suggests modified-live vaccines often provide stronger and longer-lasting protection than killed vaccines. Vaccination works best when combined with good management practices and guidance from a veterinarian.
Why do some vaccinated cattle still get sick?
Vaccines reduce risk but do not guarantee complete protection.
Cattle may still develop BRD because of:
- Heavy pathogen exposure
- Poor ventilation or overcrowding
- Stress
- Incomplete vaccine protocols
- Failure of passive transfer
- Improper vaccine handling or administration
- Concurrent disease
Vaccinated animals that become infected often develop milder disease than unvaccinated animals.
Should every dairy operation use the same vaccination protocol?
No. Vaccination protocols should be customized for each operation.
Veterinarians may adjust protocols based on:
- Herd size
- Disease history
- Housing systems
- Geographic region
- Animal movement and commingling
- Calving and weaning schedules
- Replacement heifer management
There is no single vaccination program that works best for every herd.
When should producers contact a veterinarian?
Producers should contact a veterinarian if they notice:
- Increased coughing or respiratory illness
- Fever outbreaks
- Increased calf deaths
- Poor response to treatment
- Reduced growth rates
- Recurring pneumonia problems
- Concerns about vaccine timing or effectiveness
A veterinarian can help develop a herd health and vaccination program tailored to the operation.
What is the outlook for cattle with BRD?
Many cattle recover with prompt treatment, but severe disease can cause long-term lung damage, poor growth, decreased milk production, or death.
A combination of strong management practices, proper nutrition, stress reduction, and effective vaccination protocols offers the best protection against BRD in dairy cattle.
Acknowledgment
This FAQ was developed using content from WSU’s Veterinary Medicine Extension.
This information is not meant to be a substitute for veterinary care. Always follow the instructions provided by your veterinarian. Washington State University assumes no liability for injury to you or your animals incurred by following these descriptions or procedures.