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Pneumonia is a cause of major economic loss for the cattle industry, with estimates for the annual cost of the disease running to in excess of £60 million. The costs per individual case will depend on a number of factors but are estimated to be in the region of £84. These costs are associated with decreased production, higher levels of mortality and increased veterinary and labour costs. The immediate impact of the disease is often very apparent with the loss of animals, medicines bills and the increased labour requirements being easily appreciable for the producer however, the long term impact should not be underestimated.

 

The greatest loss is that incurred by the impact the disease has on growth rates. Pneumonia can cause irreversible damage to the lungs meaning that even if an animal recovers; its lifetime performance will suffer and it will be more susceptible to future disease challenges. The reduced daily live weight gains means a longer finishing time resulting in increased production costs thus further squeezing already tight profit margins. Studies conducted in UK in abattoirs found that the growth rates for animals with damaged lungs could be reduced by as much as 202g per day and that these animals were much more likely to grade poorly.

What Causes Pneumonia?

Pneumonia is an interaction between the various infectious agents (whether bacterial, viral or both) and the environment. An animal's susceptibility to the disease will be determined by a number of factors such as their vaccination status, whether they are suffering from another disease and probably most importantly stress (brought about by events such as weaning, housing, transport or other management procedures).

The important viral causes of respiratory disease are Infectious Bovine Rhinotracheitis (IBR), Bovine Respiratory Syncytial Virus (BRSV) and Parainfluenza-3 virus (PI3). Bovine Viral Diarrhoea (BVD) may also be associated with pneumonia in some herds due to the negative effects it has on an animal immune status. These viruses can cause disease by themselves or damage the defence mechanisms of the upper respiratory tract and predispose to secondary bacterial infections of the lungs. There are a large number of bacteria that can cause either primary lung disease or secondary to viral compromise of the lung defence mechanisms. The important bacteria associated with pneumonia are; Mannheimia haemolytica, Pasteurella multocida, Histoophilus somni and Mycoplasma Bovis.

An accurate diagnosis of the cause(s) of pneumonia is important so that the correct treatments are given and that steps can be taken to prevent future disease using appropriate vaccines. Producers should contact their veterinary surgeon as when they are faced with an outbreak of disease so that investigations can be carried out to identify specific causes and risk factors that contributed to the outbreak. Once identified appropriate recommendations and management changes can be implemented to reduce the likelihood of future outbreaks

Laboratory testing enables identification of the causative viruses and bacteria and enables decisions to be made on how best to prevent future outbreaks. To investigate the cause of pneumonia your veterinary surgeon may collect nasal swabs, perform lung washes (broncho-alveolar lavage); or collect blood samples (animals will be blood sampled twice approximately 3 weeks apart). If you are unfortunate enough to have an animal die your vet may suggest a post-mortem examination.

The results of the diagnostic testing are useful when making decisions about whether to institute vaccination programmes to prevent future disease outbreaks In combination with improvements in management practices, vaccination programmes make up a key component of pneumonia control programmes on farm. Vaccines are now available which will provide effective control of the most common viral (and some of the bacterial) causes of pneumonia and should be used prior to high risk periods to minimise the risk of disease. Vaccination programmes need to be tailored to the circumstances on individual farms and care must be taken to ensure vaccines are handled and administered in accordance with the manufacturer's recommendations in order to ensure their effectiveness.

Treatment options?

When faced with an outbreak of calf pneumonia the first priority is treatment of the affected animals and to minimise the spread of disease within the group. Treatment will be most effective if it is given as early as possible in the course of a disease; so it is important that animals with pneumonia are rapidly identified and treated. Given the large number of different bugs that can cause pneumonia, treatment tends to be symptomatic with a broad spectrum of effect with antibiotics and anti-inflammatories being frequently used.

Antibiotics are the main component of most treatment regimes and there is a wide selection of products available. You should speak to your veterinary surgeon to decide on which antibiotic is most appropriate for your unit.  The exact choice of antibiotic is dependent upon a number of factors, including your vet's previous experience on the farm and elsewhere and also reported susceptibility patterns. There are also a number of practical considerations such as cost, ease and frequency of administration, potential carcass damage and for some products the issue of human safety that can impact on antibiotic choice. Whichever antibiotic your veterinary surgeon prescribes it is important to ensure that you give the appropriate dose for the animal's size and always give the full course.

Prevention is better than cure!

The prevention of pneumonia in calves is more desirable than having to treat in the face of an outbreak. Prevention consists of both vaccination programmes and establishing and maintaining management practices which reduce the risk of disease. Mixing animals of different of ages or from different sources within the same airspace will increase the risk of respiratory disease.

Think about how you use your buildings and how well they are working. Avoid overcrowding and housing animals of different ages in the same airspace. In order to reduce the risk of pneumonia it is important that sheds are well ventilated; if you are having repeated problems with pneumonia in specific sheds it would be sensible to seek advice on how to improve the ventilation. Changes to buildings will involve some investment, but don't underestimate the potential return from reducing the incidence of pneumonia in your stock.

Good ventilation is important to;

• - Remove excess water vapour.
• - Remove excess heat generated by the stock
• - Remove micro-organisms, dusts and gases.
• - Provide a uniform distribution of air.
• - Provide a correct air speed for stock.

Do not underestimate the impact of the environment on diseases such as pneumonia; If the environment is poor, even high levels of immunity will not prevent infection. Look out for cobwebs near outlets and condensation on the underside of roof panels as these are signs of poor ventilation. Keep humidity to a minimum by ensuring good drainage and regularly cleaning out sheds. Dry bedding is important to help reduce humidity in the shed and helps keep younger animals warm.

Pneumonia is an extremely costly disease and all producers should think about how to prevent it and know how to rapidly identify and treat it. Like any disease prevention is better than cure; pneumonia is best prevented by a combination of good management, appropriate building design and ventilation, and effective vaccination against the major pathogens on that particular unit well before the risk period.

Dr Tim Potter BVetMed PhD MRCVS

Veterinary Surgeon and Consultant. Westpoint Veterinary Group

 

Tim Potter is internationally recognised for his expertise in calf health and treating pneumonia. He provides a consultancy service for farmers all over the UK to reduce the health and financial impact of respiratory disease in cattle.