Bovine Respiratory Disease

What causes BRD?

Usually pneumonia is caused primarily by a virus followed by secondary bacterial infections. The animal’s environment will be a major contributing factor as to whether it is likely to succumb to respiratory disease.

1. Infectious Agents 

Viruses - Cases of BRD typically originate from a primary viral infection such as: 

• Respiratory Syncytial Virus (RSV)

• Parainfluenza 3 virus (PI3) 

• Infectious Bovine Rhinotracheitis (IBR) 

• Bovine Viral Diarrhoea (BVD) 

• Life stage 

Bacterial Infection - These act as a secondary attack after damage from initial viral infection, utilising the animal's reduced immunity. 

Parasites - Lungworm can cause irreversible damage to an animal's lungs and can lead to further respiratory disease if not treated. 

2. Environment 

Environmental factors that may contribute towards BRD include mixing stock (newly purchased stock mixed with current stock), weather and nutrition. 

3. Animal 

Breed - Some breeds have a lower lung capacity or less mature lungs and these factors contribute to the animal's susceptibility to BRD. 

Age - Younger stock have a weaker immune system than mature stock

Signs of BRD 

There are various signs that are associated with calf pneumonia, including:  

• Respiratory distress 

• Nasal discharge

• Coughing 

• Rapid, shallow breathing or mouth breathing 

• Loss of appetite 

• Weight loss or failing to gain weight 

• Signs of pain 

• High temperature (>39.5°C/103F) 

• In some cases death 

Treating BRD 

Affected calves require extra nursing and treatment with antibiotics and anti-inflammatory medicines. Treatment should be discussed with your vet. To minimise the  risk of spread of disease, sick calves should be isolated from the rest of the herd as soon as signs are spotted. 

Antibiotics control primary and secondary bacterial infections. Used with an antibiotic as an adjunctive therapy, the anti-inflammatory will aim to: 

• Reduce temperatures

• Reduce coughing 

• Reduce pulmonary congestion 

• Reduce relapse rate 

• Prevent residual lung damage 

• Combat the effects of bacterial toxins 

Control of BRD

There are a range of actions that can be implemented to prevent or limit the severity of outbreaks. These actions include: 

Housing conditions - A well ventilated building reduces the risk of pneumonia. It is also important to allow sufficient space for animals as overstocking can lead to stress and spread of infection. 

Vaccination - Calf pneumonia viruses are not controlled by antibiotics, but may be prevented by vaccination. The choice of vaccines should be discussed with your vet. 

Bought in stock - Avoid mixing calves from different sources (e.g. bought in stock and existing stock) until a full health check has been conducted. 

Cleanliness and biosecurity - Routine cleaning and decontamination will help reduce the spread of pneumonia. Shared feeders should be routinely cleaned to minimise the spread of BRD and fresh water should be readily available.  

Colostrum - An adequate intake of colostrum is critical in the first six hours of a calf's life to help develop a healthy immune system.  

Stress on calves - Weaning, transporting, disbudding and castration could all weaken a calf’s immune system and make it less able to fight off pneumonia infections.