SCOTTISH sheep keepers are being urged to tackle the rising incidence of a fatal and infectious lung condition in their flocks.

Ovine pulmonary adenocarcinoma, traditionally known as Jaagsiekte, is caused by a virus which infects cells in the lung leading to tumours. It has been recognised as a cause of sheep losses by generations of flock managers, and manifests itself in the later stages by the accumulation of fluid within the affected animal's lungs, effectively causing them to drown.

In recent years, surveys at sheep abattoirs and of fallen stock have demonstrated the reach and severity of OPA, and according to Livestock Health Scotland, the disease is now being diagnosed in all regions of Scotland and is probably impacting on all breeds.

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As reported in last weeks' The Scottish Farmer, in the absence of an accurate laboratory test for the disease, researchers at Scotland's Moredun Research Institute have taken to scanning sheep's lung as a diagnostic tool which can identify OPA tumours at an early stage.

With the support of those experts from Moredun, SAC and sheep veterinarians, Livestock Health Scotland and NFU Scotland this week produced a brief guide to OPA, its role in different flocks and the need for sheep keepers to discuss an OPA strategy with their vets.

Livestock health Scotland chairman Nigel Miller, former NFUS president and a qualified vet, said: “Like other 'iceberg' diseases, OPA can establish unseen within a flock until infection rates rise and start to erode performance and trigger increased mortality.

“With no specific laboratory screening available, control is a real challenge and intervention is crucial at two levels. In OPA affected flocks, action is needed to reduce infection rates, and in those flocks unaffected by OPA, you must seek to maintain disease freedom," he advised.

“The introduction of ultrasound lung scanning provides a much-needed diagnostic tool. Through the identification of early lung lesions, scanning can pinpoint risk animals before clinical disease is apparent. Lung scanning has a role in a test and cull programme in OPA affected flocks but may also be used to screen purchased breeding stock to reduce the risk of introducing disease into clear flocks."

NFUS animal health policy manager Penny Middleton added: “OPA has been cropping up more and more as a priority disease which producers are very concerned about. The focus has mostly been from flock owners concerned about buying in the disease, knowing that control can be difficult.

“Lung scanning, whilst it has limits, is a useful tool to help buyers reduce their risk of introducing OPA into a clean flock, as well as offering affected flocks the option of scanning the flock and removing infected sheep whilst they still have some value and reducing the exposure of other sheep in the flock," she said.

“Industry needs to start asking for this service and encouraging vets to undergo the training to be able to offer this service more widely.”

For in-depth news and views on Scottish agriculture, see this Friday’s issue of The Scottish Farmer or visit www.thescottishfarmer.co.uk