Bluetongue – how the Dutch are coping

Having witnessed bluetongue on cattle and sheep farms in the Netherlands, Dutch surveillance vet Daan Dercksen warned UK livestock producers that bluetongue symptoms can often be similar to many other livestock diseases, so vigilance is key.  

Sheep

“In some outbreaks of orf in adult sheep, swelling of the lips and muzzle occurs, which may be confused with bluetongue,” explained Mr Dercksen. Single or multiple legions may be mistaken for foot-and-mouth disease, but the classical sign of bluetongue is a swollen face which is absent in cases for FMD.  

“Haemonchis, or chronic fluke infection with a bottle jaw may present similarly to bluetongue, but examination of the eye area will reveal marked anaemia.  

“Strawberry footrot in its early stages could also be confused with bluetongue and early contagious ovine digital dermatitis (CODD), particularly in a flock outbreak will also produce legions at the coronary band –junction between hoof and foot- but unlike bluetongue, the hoof case is rapidly shed,” he explained.  

Cobalt or vitamin B12 deficiency may also be confused with bluetongue as will nasal bot fly infestation, so its vital accurate diagnosis of suspected disease is obtained.

Cattle  

Malignant catarrhal fever (MCF) – a herpes virus causing enlarged lymph glands and inflammation of the mucous membranes – is the main differential diagnosis in cattle, reckoned Mr Dercksen. “However animals with MCF will have far greater erosion around the muzzle coupled with more profuse nasal discharge than bluetongue.

“FMD could also be confused if oral discharge is excessive, but cases of FMD present with drooling saliva which is absent in bluetongue infected animals.” 

• For more on how Dutch farmers are coping with bluetongue see this Friday’s Farmers Weekly (5 October)