Ovine Pulmonary Adenocarcinoma (OPA) is a viral-induced lung cancer in sheep, primarily caused by the Jaagsiekte sheep retrovirus (JSRV). The disease is characterised by the uncontrolled growth of neoplastic cells in the lungs, leading to chronic respiratory issues and significant decline in overall health. OPA is highly contagious, spread through aerosolised virus particles via coughing or nasal discharge, making it a significant concern for flocks, especially in areas where the virus is endemic.
Infected animals typically exhibit symptoms such as weight loss, difficulty breathing and exercise intolerance, along with a characteristic “fluid-filled” or “barrel-shaped” chest appearance due to the accumulation of serous fluid in the lungs. The clinical course of the disease is often slow, and animals may live with subclinical symptoms before showing overt signs of illness.
Diagnosis of OPA is confirmed through histopathological examination at post mortem. OPA can be screened for through ultrasound. There is no treatment for OPA and removing suspected cases early, minimises the risk to the flock and allows some value to be recouped before they waste away. Additionally, management strategies focus on biosecurity measures, such as isolating infected animals, and reducing environmental stressors to lower the risk of transmission.
We are fortunate in that several of our vets are specifically trained in OPA scanning.
