Ovine Pulmonary Adenocarcinoma (OPA)
Ovine Pulmonary Adenocarcinoma (OPA), also known as Jaagsiekte, is a contagious lung tumor in sheep caused by the Jaagsiekte Sheep Retrovirus (JSRV). This disease affects the lungs, replacing normal lung tissue with tumor growth, which impairs lung function. It's a chronic condition that is unfortunately fatal and is more common in sheep aged between two to four years, although it can affect sheep as young as two months and as old as 11 years.
Symptoms and Diagnosis of OPA 🩺
OPA is characterized by progressive respiratory distress and weight loss despite a good appetite. Affected sheep may show signs of rapid breathing, especially after exercise, and may have a watery nasal discharge. This discharge is highly infectious and can spread the virus to other sheep.
Diagnosing OPA can be challenging. The "wheelbarrow test," where fluid flows from the nostrils when the sheep's head is lowered, is a classic sign. However, not all sheep with OPA will show this symptom. Post-mortem examination of the lungs is the gold standard for diagnosis.
Treatment of OPA 💊
Unfortunately, there is no treatment for OPA. Once clinical symptoms appear, the disease is usually fatal. Affected sheep should be isolated and culled to prevent the spread of the virus.
Prevention of OPA 🛡️
Preventing OPA involves maintaining a closed flock and avoiding the introduction of infected animals. Regular inspection and culling of affected sheep can help manage the disease. Ultrasound screening is a useful tool for early detection, allowing for the culling of infected sheep before they show clinical signs.
Good biosecurity practices, such as double fencing to prevent contact with neighboring flocks and minimizing close confinement, can also help reduce the risk of transmission.