Which animals have blue tongues and why

Bluetongue is a non-contagious infectious disease that is transmitted by stinging insects. The pathogen is the Bluetongue virus, an orbivirus that occurs in 24 different serotypes. The virus is not dangerous to humans. Meat and dairy products can be consumed without hesitation. Sheep and cattle, and rarely goats, are affected by bluetongue disease. Bluetongue is a notifiable animal disease.


The disease is transmitted by various Culicoides mosquitoes (approx. 1-3 mm in size) from the midges family. In Germany, the Netherlands and Belgium, Culicoides dewulfi is the main vector. These sucking insects ingest the virus that is circulating in the blood of an already infected animal and transfer it to another animal when it is stung.

The disease occurs predominantly during the summer rainy season. This seasonal manifestation of the disease is closely related to the flight time of the Culex mosquitoes. The epidemic climaxes are therefore in warm, humid weather and during the swarming period. The mosquitoes still fly at temperatures of up to around 8 ┬░ C and are mainly active between dusk and dawn. Infected mosquitoes can be moved up to 200 km by winds and then spread the pathogen in the new location.

Symptoms and Diagnosis

As a cyclical general disease with an incubation time of between 1 and 8 days in sheep and 5 to 12 days in cattle, it shows the following appearance: Sometimes restless gait, as well as teat necrosis. The udder skin turns dark and dies. The changes to the muzzle and coronet heal within a few days, the necroses on the udder remain visible for a long time. Sheep show symptoms such as fever, apathy, swelling and cyanosis in the mouth and tongue. The coronary hem on the claws reddens and becomes painful, lameness can result.

According to the Friedrich Loeffler Institute, a typical clinical picture is usually only found in sheep. But even with this species, no reliable diagnosis can be made on the basis of the clinical picture. Very similar symptoms are also caused by other viral infectious agents such as the foot and mouth disease virus, Akabane virus, or border disease virus.

Since the bluetongue virus is associated with red blood cells, whole blood should be used for laboratory testing. There is both direct pathogen detection and indirect antibody detection.

Consequences for animal owners: situation in Rhineland-Palatinate

Bluetongue serotype 8 (BTV-8) was detected in December 2018 in Ottersweier in Baden-W├╝rttemberg (district of Rastatt) and in January 2019 also in companies in Rhineland-Palatinate. Restriction areas with a minimum radius of 150 km were set up around the outbreak operations, which affect the whole of Rhineland-Palatinate. The restricted area must be maintained for at least two years.

In order to prevent the spread of the disease in Rhineland-Palatinate, the LUA will issue an animal health order. According to this, everyone who keeps animals susceptible to the bluetongue virus in the restricted area - i.e. all ruminant species such as z. B. cattle, sheep, goats and wild ruminants in enclosures - notify the competent veterinary authority of the district administration immediately, if this has not already been done. Signs of illness that give rise to fear of an outbreak of bluetongue must also be reported immediately.

In addition, susceptible animals may not be moved from the restricted area into restriction-free areas. This also applies to semen, egg cells or embryos. Exceptions are possible, but must be approved by the competent veterinary authority. When transporting from or through the restricted area, the transport vehicles must be cleaned, disinfected and treated with an insecticide prior to transport.


Vaccination of susceptible animals against bluetongue is recommended as it offers protection against the disease and also facilitates movement. It is voluntary, the costs are borne by the animal owner. There are BTV-8 vaccines for cattle and sheep that have been approved in Germany. For goats, the vaccine can be rededicated by the veterinarian. Animal owners should contact their farm veterinarian with any questions they may have about vaccination.

In order for animals to be considered vaccinated, the vaccination must be documented in the animal traceability and information system (HI-Tier), stating the registration number. The date of vaccination, the vaccine used, the batch used and the species of animal must be stated. Sheep and goats are recorded in relation to their herd, cattle individually, stating their individual ear tag number.

A list of approved animal vaccines is available on the Homepage of the Paul Ehrlich Institute (PEI).

For detailed information on vaccination against the bluetongue virus, see the Permanent Vaccination Commission for Veterinary Medicine (StIKo Vet) at the Friedrich Loeffler Institute.