Bluetongue is potentially the most devastating disease to hit the UK, specialist sheep vet Paul Roger told farmers at last night’s bluetongue information meeting organised by Farmers Weekly, NSA, LAA, EBLEX and NBA.
“Bluetongue is associated with vascular damage and this is how it causes most problems. The main symptoms are swelling of the head and neck and a classic bottle jaw appearance.
“Also there is erosion of the flesh around the edge of the nostrils and swelling around the eyes.”
But, warned Dutch vet Daan Dercksen, not all animals will show these symptoms. “Often animals will show very mild symptoms and in cattle it may be as little as linear erosion around the base of teats. In suckler cattle it may be that you notice a calf not thriving and on closer inspection see the dam has erosion of the teats and hence isn’t allowing the calf to suck properly.”
The UK cases where post mortem examinations have taken place have shown clear erosion of the gums and palate and blistering and erosion of the tongue, said Mr Roger.
Detailing the Dutch experience Mr Dercksen explained that the disease had first been diagnosed in a flock of sheep in August 2006. “This flock had one dead lamb and once sick ewe. The second case was also in sheep and there was one dead ewe and two other sick ewes, this second farm was on the German border and close to Belgium too, so immediately we had three countries involved.”
“Affected stock must receive supportive fluid therapy, be kept out of the sun and receive easily digestible food.”
At the end of August it was diagnosed as serotype eight and it also spread to France then too, he said.
“Many sheep in Holland have been seen trying to cool their noses due to the fever they suffer with bluetongue. Some farmers think they are just drinking, but they spend all day with their noses in water. On a practical level this means the water has to be changed regularly as it becomes dirty with the mucous from the sheep.”
Some sheep have also suffered muscle damage due to the disease and this can lead to severe lameness, as the muscles become contracted, explained Mr Dercksen. “There are also major fertility problems in rams affected by the disease, with either very poor quality sperm or no live sperm at all.”
In terms of disease spread there are two midge species involved, Culicoides Obseletus and Culicoides Dewulfin. “In 2006 Obseletus was the major problem, whereas in 2007 it is Dewulfin which has been spreading disease most.”
However, Holland hasn’t seen the disease being spread by Culicoides Imicola, the midge commonly associated with BTV8. Dewulfin likes being inside, so housing stock to avoid contact with midges is of no benefit either.”
There are various treatments Dutch farmers have used, but overall it is round the clock care which is helping save most animals from the disease, he told farmers present. “This may be more difficult for UK farmers with large numbers of sheep, but it is the only way to tackle this disease at the moment. Affected stock must receive supportive fluid therapy, be kept out of the sun and receive easily digestible food.”
With a vaccine possibly available next year Mr Drecksen said he personally favoured compulsory vaccination aimed at eradicating the disease, but this would need the cooperation of Holland’s neighbouring countries.
“And at present not all Dutch farmers are in favour of this approach as bluetongue hasn’t caused many problems in the far north of Holland yet, so these farmers are still relatively naïve about how bad the disease could get.”