FAQs - Cattle Specific

Bluetongue causes fever (temperatures up to 40^oC), nasal discharge, swelling and ulceration of the mouth, swollen teats, runny eyes, lethargy, drooling saliva, and swelling of the head and neck. In dairy cattle there can be huge losses in milk yield and a reduced resistance to other diseases such as mastitis, metritis and lameness.

It can be hard to spot in cows as infection is often subclinical (many animals show no visible signs), so regular stock inspection is necessary – particularly around the nose and mouth, and the coronary band – to catch signs early. Secondary bacterial infections (commonly respiratory disease) often follow bluetongue infection. Cows can remain viraemic (infectious) for up to 60 days.

There is no cure, but relieving the symptoms and nursing the sick animal means cattle can survive the disease. Medications which are most likely to help are antibiotics and anti-inflammatories.Cows should improve 48-72 hours after treatment, with full recovery in 7-10 days.

All stock bitten by midges carrying the virus will be infected and a potential risk for transmitting disease, but not all will show clinical signs.

Yes, it affects all ruminants without immunity.

Via midges (Culicoides species), often referred to as the disease “vector”. Britain has 47 midge species – only a few of which of which transmit BTV. The female midge requires a blood meal to mature a batch of eggs. When she bites an infected animal, the virus multiplies inside her over a period of days (depending on the temperature). She then bites another animal and passes on the virus. Midges breed in wet leaf litter, mud, tree holes and stream banks.

Theoretically it may be possible to spread the virus on contaminated needles but the risk of this is extremely low and has never been identified in the field.

BTV can’t be contracted or spread through meat or milk and there is no cow to cow transmission. The key risk factors for British livestock are animal movements from infected areas and windborne midge movement.

It is known that this has occurred in some infected pregnant cattle. Such calves may born infected but it is not clear as yet how important this is in disease transmission.

No.

Because the vector is an insect, there are no guaranteed methods to prevent transmission of the disease. Control by avoiding or removing midge breeding grounds may reduce vector numbers, and Defra and SEERAD advise keeping stock away from low-lying damp grazing, particularly at dawn and dusk. Dung heaps or slurry pits should be covered or removed, and their perimeters (where most larvae are found) regularly scraped. A deltamethrin-based pour on product, Butox SWISH, has also been shown to be effective at killing midges on treated cattle for up to 4 weeks, and other insecticides may have some effect. However preventing all midge bites is virtually impossible, so vaccination is the key method that can prevent disease spread.

Vaccination of all animals is important as even subclinically affected animals will act as a reservoir of infection and allow the disease to spread further, which would keep the disease in circulation for years to come. In addition, it is impossible to predict what effect the disease might have on any individual herd, so not vaccinating is a huge risk.

BTV is a notifiable disease and restricted zones around outbreaks are required and controlled by EU legislation. A 20km radius zone is put immediately around the infected holding, beyond that is another 80km Protection Zone (PZ), followed by a Surveillance Zone (SZ) of at least 50km. Within the total 150km zone, there are movement restrictions on livestock, carcases, semen and embryos to prevent transporting the virus to different parts of the country.

Because this vaccine has a provisional licence there is no data currently available on the use in pregnant or lactating animals so we advise speaking to your vet before vaccinating such cows. The vaccine can be used on animals over one month of age.

Plan how you will get all stock in to vaccinate them and make sure that when you get the vaccine, you will be able to do the whole herd in one go. Also be aware of any certification or declaration you may require according to Defra rules should you want to move your animals outside the PZ. To reduce the risk of disease in the meantime, vector control as per question 9 should be considered. As the vaccine is not licensed for use at the same time as any other products, it is worth planning the timing of other necessary vaccinations and treatments accordingly.