Beating the silent killer stalking Scottish flocks

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It HAS been called the “unspoken” disease in the sheep industry and that is not because its scientific name Ovine Pulmonary Adenocarcinoma (OPA) is a bit of a mouthful nor because its other name of Jaagsiekte is difficult to pronounce.

It is, as several farmers said yesterday at a sheep health meeting at the Oatridge campus of Scotland’s Rural College, because any admission by sheep producers that the disease is in their flocks will devalue their sales.

These farmers – who did not want to be identified – confirmed the information provided by Chris Cousens, of the Moredun Research Institute, that sheep in around about 10 per cent of the flocks in Scotland have the fatal disease.

In fact, they thought the estimate could be on the low side as few farmers ever acknowledged their sheep were infected, a possibility endorsed by more than 5 per cent of sheep in one veterinary investigation office showing OPA infection.

The disease briefly hit the headlines when Dolly the sheep succumbed to OPA but has otherwise remained largely unacknowledged or understood.

Cousens said there were many aspects of dealing with OPA that still had to be developed, including getting an accurate diagnosis on live sheep and then producing a vaccine to control it.

Infected sheep are often skinny, they tend to puff as their lungs are full of fluid and they tend to be “snotty”, which is a non-technical term for having a running nose.

But, while some infected sheep displayed these symptoms, others did not and this made preventing the spread of the disease more difficult.

It had been found in all sheep breeds but, anecdotally, there seems to be a fair amount of infection in the Blackface breed. Cousens said that, while some English breeders called it a “Scottish” disease, she and her colleagues at Moredun were taking calls from all over the UK from producers losing their stock and vets wanting advice.

While New Zealand claims not to have a problem with OPA, one delegate yesterday explained how one New Zealander was coping with the disease which is prevalent in all the main sheep producing countries in the world; Jaagsiekte is an Afrikaans word for “trail death” as sheep being herded often just collapse en route.

Cousens proposed the best control at present was to operate high biosecurity on the farm and to inspect bought-in stock for coughs and runny noses. Any suspect animals were best culled.

When asked when a vaccine might become available, Cousens said there was nothing on the horizon. Moredun had tried to provoke an immune response for a vaccine but initially promising results had not been followed by success at field trial stage.

She also said the government was not prepared to fund a programme to find a vaccine at present: “The pot of money they have for research is smaller than it used to be and I can understand that at the present.”

She later added that it was “extremely unlikely” any commercial company would come in to back up the research work as it was not “near market” and they would not see a quick return on their investment.

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