Clinical Signs of the Bluetongue Virus
The BVA, British Cattle Veterinary Association, Goat Veterinary Society, Sheep Veterinary Society and Veterinary Deer Society urge all ruminant owners, shepherds and veterinary surgeons to be vigilant and to make themselves aware of the clinical signs of disease. Suspicion of disease should be reported to your local Divisional Veterinary Manager.
Clinical signs of bluetongue
Veterinary surgeons should be aware that sheep are showing clinical signs but less typically, cattle in the Netherlands have also shown clinical signs too. European ruminants are naïve to the virus and there is little data on the disease in indigenous cattle and sheep. It is known that there is variation in clinical signs and severity between sheep breeds.
Sheep - signs of infection
These vary in severity depending on the strain of virus and breed of sheep. Clinical signs include
- fever (typically ~42 ºC)
- swelling of the head and neck
- inflammation and ulceration of the mucous membrane of the mouth, nose and eyelids
- lameness
- muscle degeneration and leaking of blood or serum from blood vessels into the surrounding tissues
- haemorrhages in the skin and other tissues
- respiratory signs such as froth in the lungs and an inability to swallow
- a high mortality rate
Sometimes, although it is rare, there may be some discolouration and swelling of the tongue. Differential diagnoses include FMD, CODD and Photosensitivity.
Cattle - signs of infection
Although Bluetongue usually causes no apparent illness in cattle or goats, cattle are displaying clinical signs during the current outbreak in Western Europe. Cattle may
- be febrile and may show dullness
- exhibit nasal discharge, lachrymation, with swelling and erosion of the nasal planum, mouth and teats
- show lameness due to coronitis
Differential diagnosis includes FMD, Malignant Catarrhal Fever and Mucosal disease.
Other ruminants - signs of infection
Although goats, deer and camelids may carry the virus it may be mild or inapparent, with only a transient viraemia. Goat keepers should be aware that, in 2007, similar symptoms to those seen in sheep were reported.
Further information
Differential diagnosis of bluetongue in cattle and sheep - article from In Practice (May 2008)
See the clinical signs and pathology in British sheep and cattle infected with the bluetongue virus serotype 8 - article from The Veterinary Record (August 2007).
Read this practical guide to bluetongue in sheep and cattle including images of diseased animals - article from In Practice (June 2007).
A provisional full disease profile is available on the Defra website.
Return to the Joint campaign Against Bluetongue