Pneumonia in calves is the result of a complex interaction between viral and bacterial pathogens, environmental stress factors and the animal’s own resilience to disease.

Calf pneumonia causes inflammation and damage of the lung tissue and airways – compromising lung function. In severe cases, the damage is irreversible and can result in death. However, even mild cases of pneumonia can significantly increase the cost of production.

Environmental factors include low environmental temperatures; high humidity; poor ventilation; and also direct draughts onto calves themselves. The relationship between seasons and outbreaks may also be related to management practices including calving pattern and mixing of different ages of calves.

Causes of pneumonia

Infectious agents involved in causing pneumonia include mannheimia haemolytica, haemophilus somnus, infectious bovine rhinotracheitis (IBR), bovine respiratory syncytial virus (RSV) and parainfluenza III virus (PI3), along with many other bacteria and mycoplasma species and viruses.

Other factors that contribute to pneumonia are poor housing ventilation; overcrowding; poor nutritional status; and presence of older animals.


Symptoms of pneumonia

There are two forms of the disease: Chronic and acute. Both of these forms of the disease cause production losses as there is a reduction in liveweight gain and can possibly result in death.

Clinical signs of calf pneumonia include:

  • Dull and depressed;
  • A temperature of greater that 39.5º;
  • Increased breathing rate and effort;
  • Coughing;
  • A nasal discharge which is initially clear and watery, but becomes thick and pus-like as the disease progresses.


As with most outbreaks, prevention is better than cure. Given the multi-factorial nature of the disease, good calf pneumonia control programmes rely on implementing an appropriate vaccine strategy, alongside improvements to management practices to reduce the risk of disease.

Good colostrum intake is the first and most important step to provide the new-born calf with good immunity.

Using the 1,2,3 rule:

  • 1. Use the first milk (colostrum) from the cow;
  • 2. Feed the calf colostrum within the first two hours of birth;
  • 3. Calves must be offered at least 3L of good quality colostrum