Vet's column: Stress can be a major factor in calf pneumonia

Housing and weaning are two of the most stressful events in a suckler calf’s life and both come close together. Stress is an important factor when considering pneumonia and it is not uncommon to see respiratory disease in calves soon after housing and weaning.

A case of pneumonia was estimated to cost on average £82 per calf 20 years ago, so it is reasonable to assume that would be into three figures now based on medicine costs, loss of performance and labour costs.

Respiratory disease is caused by interplay between viruses, bacteria and, as already mentioned, stress. The primary causes of pneumonia are viral in origin, with bacteria often invading secondary to this once the lungs have been damaged and making the problem worse.

The infectious agents will survive longer when the environment is warm and humid, which is why warm, wet days soon after housing can lead to a spike in disease. Cattle produce large amounts of water through their breath, saliva and urine, so there needs to be good drainage and ventilation in the buildings to reduce the levels of moisture in the air. This subsequently reduces the level of infectious pathogens and ammonia that damages the lining of the calf’s respiratory tract leaving it more susceptible to infection.

It is important to reduce stress as much as possible, so while weaning and housing calves cannot be avoided, there is a benefit from avoiding management tasks such as castration or de-horning around the same time as well as avoiding the mixing of groups.

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Vaccination has a key role in reducing the levels of pneumonia on farm, especially as we need to be careful regarding antibiotic use, with an emphasis needing to be on preventative medicine rather than cure.

There are several different pneumonia vaccines on the market in the UK each providing protection against slightly different infectious agents. There are differing routes of vaccination, and each will have a slightly different onset and duration of action, so it is important to chat to your vet before deciding which one is right for your farm.

It is important to cover the main respiratory pathogens as well as any that have caused disease on the farm in the past.

The main viruses causing disease on farm are Bovine Respiratory Syncytial virus (BRSv) and Bovine Parainfluenza 3 virus (BPi3), while there are many different bacterial pathogens such as Histophilus, Mycoplasma, Mannheimia and Pasteurella, if you are not sure which pathogens you have on your farm, it is important to talk to your vet as they can help you find out and there may be subsidised testing available if you are experiencing problems with pneumonia.

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Intranasal vaccines are available which are often single shot and provide rapid onset of immunity but these usually only cover the viral pathogens and only provide protection for 12 weeks.

Vaccines that are given by injection usually provide cover for the main viruses and differing bacterial pathogens depending on their makeup. These often require an initial dose followed by a booster a few weeks afterwards.

Usually, immunity takes a few weeks to develop after this so ideally the course needs to be timed so immunity has developed to provide protection at weaning and housing.

A combination of the two types can also be used, so again it is important to speak to your vet in order to come up with the right regime for your farm.

Vets play a vital role in helping to manage pneumonia on farm beyond simply providing antibiotics. We can offer a wide range of tests to identify the pathogens causing the disease on your farm and come up with a prevention strategy going forwards thus avoiding the acute and chronic effects of pneumonia, so if you are experiencing issues get in touch with your vet sooner rather than later, it may well save you money in the long run.