Sheep pneumonia? Here’s how to protect flock health
Sheep pneumonia continues to challenge producers across southern Australia, but MLA-funded research including minimising stress and managing environmental factors where possible.
Led by Dr Steve Cotton of Dynamic Ag and Dr Joan Lloyd from Joan Lloyd Consulting, the project aims to better understand the disease’s prevalence, potential risk factors and strategies to minimise its impact.
Latest results
Steve said initial research findings were shared last year (check out the winter 2025 edition of Feedback at on the MLA website), but further sampling and analysis indicates the disease remains common, with prevalence varying depending on the season or year.
“In 2024, around 22% of tested sheep were positive for the sheep pneumonia pathogen Mycoplasma ovipneumoniae. More recent testing suggests prevalence has declined, with only 14.8% of animals testing positive in 2025,” Steve said.
He noted this reduction may reflect improved seasonal conditions and reduced nutritional stress in some regions.
While occurrences vary between properties, the research confirms the bacteria continues to be widely present in west Victorian sheep populations.
The study sampled 750 ewes and wethers each year between 2024–25 and found significant variations within individual flocks. Pneumonia impacted between 7–93% of sheep in the affected flocks involved in the study.
Importantly, the study found no clear links between pneumonia and breed, sex or geographic region.
Steve said early data suggested higher rates of infection in composite sheep, but this may be related to management factors such as joining ewe lambs at a younger age or more intensive feeding systems rather than breed itself.
The research also supports previous findings that infection can be widespread within a flock, with some animals acting as chronic carriers that spread the bacteria to lambs soon after birth.
Stress remains a key trigger
One of the strongest patterns emerging from the research is the link between stress and the development of pneumonia.
According to Steve, the number of times lambs are handled after weaning appears to increase the likelihood of infection, with the stress caused by normal on-farm activities such as mustering, yarding, shearing or drenching possibly allowing the bacteria to proliferate.
Environmental conditions can also play a role. Sudden changes in temperature, poor seasonal conditions or nutritional constraints may reduce feed intake and increase stress levels in animals.
“These bacteria are often present in sheep populations, but stress events can allow them to multiply and lead to respiratory disease,” Steve said.
Dusty conditions can also irritate the respiratory tract and make animals more susceptible to infection.
Recognising the signs
The clinical signs of pneumonia can be subtle. Adult sheep may show coughing, wheezing, runny eyes or nose, laboured breathing after exertion, or reduced performance.
In lambs, signs such as coughing, nasal discharge, difficulty suckling and, occasionally, swollen knee joints can appear from one to two months of age.
However, in some cases, the disease may remain subclinical and be attributed to slower-than-expected growth rates.
Sheep pneumonia – what to look out forThe clinical signs of pneumonia can be subtle –here are some of the signs to look out for: Signs in adult sheep:
Signs in lambs:
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Reducing the impact on farm
While treatment options remain limited, several management strategies can help reduce the risk of outbreaks.
These include minimising unnecessary yarding events, maintaining adequate nutrition and water supply (including ensuring clean trough water where possible), and avoiding overcrowding in feedlots or containment areas.
Monitoring lamb growth rates can also help identify animals that may be affected, and slower-growing lambs may require closer inspection or management adjustments.
Future research
Antibiotic therapy is currently the most common treatment when infection is detected, but researchers are continuing to investigate longer-term strategies to reduce reliance on antibiotics.
The current project is focused primarily on understanding the prevalence and risk factors associated with sheep pneumonia. As more data becomes available, the findings are expected to help inform future research and management strategies for producers.
Eight ways to reduce the risk of pneumonia in your flockProducers can reduce the likelihood and impact of sheep pneumonia by focusing on practical management steps that minimise stress and support animal health. 1. Minimise unnecessary handling Limit the number of times lambs are mustered or yarded after weaning where possible, and combine management tasks (e.g. weighing, drenching or drafting) to reduce handling events. 2. Manage stress around key husbandry events Be mindful of stress during procedures such as weaning, shearing, crutching and transport (preparation for transport is critical), particularly during challenging seasonal conditions. 3. Maintain good nutrition and water supply Ensure sheep have access to adequate feed and clean water, especially during periods of drought, poor pasture growth or high nutritional demand. 4. Avoid overcrowding Follow recommended stocking densities in containment areas, feedlots or yards to reduce stress and disease transmission. 5. Monitor lamb growth rates Identify lambs that are growing more slowly than expected, as reduced growth can be an early sign of respiratory disease. 6. Watch for early clinical signs Look for coughing, wheezing, nasal discharge, runny eyes or laboured breathing, particularly in lambs from one to two months of age. 7. Seek veterinary advice early If pneumonia is suspected, contact your veterinarian promptly to confirm diagnosis and discuss treatment options. 8. Review flock biosecurity Consider the health status of purchased animals and monitor new stock to reduce the risk of introducing respiratory pathogens into the flock. |
