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Working together to control ovine pulmonary adenocarcinoma (OPA)

“Doing nothing is not an option”  was the unanimous opinion of the farmers, vets and sheep health experts participating at a workshop to discuss the way forward to control OPA  held at Moredun on Tuesday 5th June.  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 this insidious disease.  The workshop concluded that there is a clear appetite within the livestock industry to tackle OPA control although education is still needed regarding awareness of the disease and its transmission. 

OPA is an infectious lung cancer specific to sheep caused by a virus known as 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.

Dr Chris Cousens, Moredun, said: “We are delighted to be hosting this workshop today to bring people together from across the sheep industry to discuss how we can tackle OPA. It is imperative that we continue our research to develop and apply better diagnostic tests and tools to control the disease.”

Ultrasound scanning as a basis for test-and-cull is proving useful in tackling OPA in individual flocks as described by the researchers, farmers and vets presenting at the workshop, and the majority of delegates strongly supported this method of OPA control.  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.  As well as ultrasound screening, post mortem examination of cull sheep and feedback from abattoirs could have an important role in monitoring flocks for OPA.  

The workshop concluded that the time was right to look at developing an OPA scheme which is a significant and welcome step forward for the sheep industry.

Sheila Voas, Chief Veterinary Officer Scotland 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”.