printStock Journal Article - October 2024
Author: Emma Shattock, Elders
Reports of pneumonia in sheep, particularly lambs, have been prevalent this year. Considering that outbreaks are often stress induced, we have opportunities through good management practices to take back some control and reduce the incidence of disease.
Pneumonia is an infection and inflammation of the lungs and can be caused by a range of bacteria and viruses. One of the more common pathogens in sheep in Mycoplasma ovipneumoniae. Infection with these bacteria predisposes the sheep to secondary lung infections from other bacteria that normally live in the sheep without causing disease. As the infection develops, lung tissue becomes increasingly damaged. Affected stock may need to be treated with antibiotics as per veterinary advice.
Sheep with pneumonia may present with a cough or nasal discharge which can develop into breathing difficulty and death in severe cases. Appetite is often reduced and affected animals may stand apart from the rest of the mob. Even in mild cases, growth rates can be reduced.
Some cases of pneumonia can develop into pleurisy. This is when the lung membrane sticks to the ribcage and results in trimming at the abattoir.
A major causative factor that allows infections to flourish is stress. This can come in many forms, such as the psychological stress of weaning and handling to the physical stress of transport. Stress suppresses the immune system, making it easier for pathogens to take hold and disease to develop.
This year, in many parts of South Australia sheep have also faced nutritional stress. While they may be in acceptable condition, many may only be receiving minimum requirements for maintenance, especially when considering the need for early weaning this season. This adds another layer of stress into the system and may be responsible for the increased cases this year. Dry, dusty conditions and feeds are another predisposing factor.
Any extreme stress event could still lead to pneumonia cases, even when prior stress events have been well managed. Outbreaks have been seen in lambs that were weaned with a stress management program only to be sold and trucked several months later and succumb to pneumonia. Weaners that experience even a sub-clinical level of this respiratory disease can suffer scarring on their lungs that can lead to ill-health later in life when put under stressful conditions.
Proactive management is key in a prevention program. The use of stress management supplements at high stress events such as weaning and transport can have a big impact. These help by providing minerals and vitamins that help calm the animal and replenish what is often lost during the stress event. Treated animals usually display fewer stress related behaviours such as vocalisation and refusal of water and feed.
There are a range of different products available that vary in composition and application. Be sure to match the product to your system with sound advice from an expert.
Management to reduce other stressors is also important. This includes avoiding mixing mobs and sudden diet changes, while incorporating low stress handling techniques. As far as practically possible, avoid overcrowding and handling stock in dusty yards.
Prior awareness of how pneumonia develops provides an opportunity for producers to assess current management practices. Aim to identify key points in the program where management can be improved, particularly regarding stress. The bonus is that improvements around critical times such as weaning, transport and feedlot induction can have greater impacts beyond pneumonia control, including improvements in productivity and profitability.