Ovine Pulmonary Adenocarcinoma: Welfare Management

Key Welfare Considerations

• OPA is caused by Jaagsiekte Sheep Retrovirus (JSRV) causing progressive lung tumour welfare disease.
• Welfare deterioration is gradual — weight loss, respiratory distress, and exercise intolerance develop over months.
• The classic welfare diagnostic test involves lifting the hindquarters to cause fluid to flow from nostrils.
• No welfare treatment is available — affected sheep inevitably deteriorate and die without euthanasia.
• Early welfare diagnosis through clinical signs enables humane euthanasia before severe suffering.
• Fluid production into the airways from tumours causes the characteristic welfare 'wheelbarrow test' positivity.
• Welfare early in disease is subtly compromised — weight loss and reduced productivity precede overt welfare signs.
• Affected welfare animals shed JSRV in respiratory secretions — isolation reduces welfare transmission.
• No vaccine is commercially available — welfare management relies on identification and culling.
• Biosecurity through closed flocks reduces JSRV welfare introduction risk.
• Purchasing sheep from OPA-tested accredited flocks reduces welfare introduction risk.
• Regular flock welfare assessment including respiratory scoring identifies potential OPA cases early.
• Slaughter of confirmed welfare cases prevents further welfare suffering and reduces transmission.
• Post-mortem examination of suspicious welfare cases confirms OPA and guides flock management.
• OPA welfare awareness training for farmers enables earlier humane welfare intervention.