Ovine Pulmonary Adenocarcinoma (OPA) is a contagious lung cancer of sheep caused by a retrovirus, resulting in significant suffering and production losses in affected flocks.
OPA causes progressive suffering: affected sheep experience worsening dyspnoea, cachexia, and respiratory distress over weeks to months before death. Early culling of identified clinical cases is the primary welfare intervention, preventing prolonged suffering. Flock management to reduce JSRV transmission is essential for long-term welfare protection.