DOING nothing about OPA is not an option – that was the unanimous opinion of the farmers, vets and sheep health experts participating at a workshop to discuss the way forward to control the sheep disease, held recently at the Moredun Research Institute, Edinburgh.

In the absence of any vaccine, treatment or blood test, ultrasound scanning as a diagnostic tool to identify sheep with pre-clinical OPA could be key in helping to control the disease. The workshop concluded that although there was a clear appetite within the livestock industry to tackle OPA, education was still needed to increase awareness of the disease and its transmission.

OPA is an infectious lung cancer specific to sheep caused by the jaagsiekte sheep retrovirus. Typical signs in an affected animal are difficulty in breathing often with marked loss in weight, although clinical signs may not show for several years. OPA is commonly introduced to flocks through the purchase of apparently healthy animals carrying the virus which can be spread to other animals within the flock.

Moredun's Dr Chris Cousens said: “It is imperative that we continue our research to develop and apply better diagnostic tests and tools to control the disease.”

The meeting heard that ultrasound scanning as a basis for test-and-cull was proving useful in tackling OPA in individual flocks – but use of scanning for a national eradication scheme was thought to be a step too far at the current time. However, much discussion was raised around the possibility of a scheme which would allow individual flocks to achieve monitored OPA status in order to sell sheep certified as low risk for OPA transmission.

Chief veterinary officer for Scotland, Sheila Voas, said: “We need to work together to tackle OPA as we now have the tools to make a difference. Prevention and control of diseases such as OPA will significantly improve the health and welfare of our sheep flocks and will improve production efficiency and increase profitability for farm businesses."