Pneumonia and associated pleurisy cost the sheep industry significant amounts of money every year in lost production and downgraded carcasses, but simple management factors can help prevent these diseases.
The most common form of pneumonia is Chronic Non-Progressive (CNP) Pneumonia which can be caused by bacteria, mycobacteria and viruses. Symptoms are often sub-clinical, but affected sheep will commonly have trouble breathing, cough and pant following exercise. Pneumonia is ubiquitous and it has been estimated that on average, 24 percent of lambs in any flock will be affected by this production-limiting disease.
Sheep with pneumonia are more likely to develop pleurisy where the lungs stick to the chest wall and when this happens, affected carcasses are downgraded or condemned at processing plants.
Studies have shown that pneumonia can have a significant impact on lamb growth rates. Where more than 20 per cent of the lung surface area is affected, growth rates are halved. There appears to be no effect on weight gain where less than five percent of the lung is affected.
A number of on-farm factors are thought to be linked to pneumonia in lambs. These include shearing at weaning, slaughtering late in the season, running in a larger flock and having strong wool.
Other factors that are considered a risk include high temperatures and humidity, crowding, stress, excessive exercise, poor ventilation, low immunity and high parasite burdens.
A healthy, well-fed animal under minimal stress is less likely to develop the disease but there are other preventative steps farmers can take the minimise the risk of pneumonia.
- Keeping yarding time to a minimum.
- Dampening-down the yards with sprinklers to reduce dust.
- Keeping mob sizes small to minimise animal stress and dust inhalation.
- Avoiding shearing lambs at weaning.
- Try and reduce the extent and duration of open-mouth panting when moving lambs. Use satellite yards to reduce long-distance movement, reduce pressure on lambs when moving and make use of laneways to allow lambs to drift at their own pace.
For more information on pneumonia, see our Pneumonia and pleurisy in sheep factsheet (PDF, 102 KB)