Bovine Viral Diarrhoea (BVD) is a notoriously difficult disease to control. While eradication is regularly discussed in the media, this is not a viable route for most UK producers due to cattle population densities and the problems of maintaining good bio-security. Testing a herd’s BVD status, with bulk milk (dairy) or blood sampling (beef) has been used for some time, and indicates whether a herd is suffering from active infection, has been exposed to the virus, or is naive. A vaccination strategy can then be developed. A continual threat to a herd, even one that is managing the disease with vaccination, is the presence of Persistently Infected (PI) animals. These animals carry the virus constantly and can infect other cows. Historically, PIs have been culled, once identified. That said it is just this – identification – that has historically been the difficulty. However, Intervet has just announced an upgrade to its subsidised DairyCheck scheme to include a bulk milk PCR test that is capable of detecting a single PI animal in a herd of up to 300 cows. The test detects BVDV type 1 or 2 and a negative result indicates there are no viraemic animals in the cows and heifers contributing to the bulk tank. It should be noted that the test is only representative of those cows delivering milk into the tank. Dry cows, youngstock, or cows whose milk is being withheld need to be blood tested. Intervet says eliminating PI animals is the key to controlling BVD and upgraded DairyCheck (which also screens for IBR and lepto) will now makes it easier to develop a systematic approach to BVD control. The initial screening for PI animals should be part of an approach that includes diagnostics, identifying and culling PI animals and using a vaccination such as Bovilis® BVD to prevent new PI calves being born.

Bovine Virus Diarrhoea (BVD) infection in cattle is a widespread disease of major economic importance to cattle farmers in Scotland. As of June 1, 2015, Scotland has moved into Phase 4 of BVD eradication in Scotland. Now all cattle farms in Scotland are either ‘Negative’ or ‘Not Negative’. The ‘Not Negative’ category can be given either because the cattle have not yet been tested appropriately, or because the cattle have tested positive, but all ‘Not Negative’ farms now have movement restrictions on them – unless a cow being moved has an individual negative result or the animal is going straight to slaughter. Previously there were bulk milk tank test options, and these have been removed for the purposes of declaring a herd status. The test required to obtain a ‘Negative’ status will depend on whether your herd is a breeding herd (even one calf counts!) or a non-breeding herd, and the type and number of calves that you have in your herd. For further details, please phone Alistair or Richard, or you can read the guide HERE

BVD is caused by a virus (BVDV) which principally infects cattle but which also infects sheep and other ruminants.

Although BVDV does cause diarrhoea, the main disease occurs when BVDV infects susceptible pregnant cows in which the virus quickly crosses to the foetus.

The earlier in pregnancy that the virus reaches the foetus the more severe the disease. The most dangerous time is during the first half of pregnancy before the foetus has any immune system of its own.

If infected in the first half of pregnancy the foetus can die and be reabsorbed, presenting as infertility or 'repeat breeding'. Other infected foetuses die later and can be aborted right up to term or be stillborn.

Some foetuses however survive to term. Some are damaged and grow poorly but many are normal. All of them are persistently infected (PI) with the virus which is widespread in their bodies and not recognised by their immune system as a disease.

Generalised persistent infection (PI) of the calf with BVDV can only be established during the first half of pregnancy, when the calf’s immune system is beginning to develop.

PI calves excrete virus continuously for the rest of their lives but they may develop mucosal disease (a fatal enteric disease) at any age. If a PI cow breeds successfully she will always produce a PI calf.

BVD infection is spread and maintained through the existence of PI animals, which constantly excrete the virus. They will rapidly infect other cattle that are in close contact, and may make them more susceptible to other diseases such as pneumonia.

Control and prevention of the infection can only be achieved by applying strict biosecurity procedures, vaccination and long term control strategies, particularly in identifying the PI animals and removing them.

The control of BVD on your farm is important. Discuss it with a Parkside vet and find out more about the Scottish Agricultural College Premium Cattle or other health schemes. 

(these highlights courtesy of the Moredun Foundation)

 

Bovilis® BVD 50-dose multi-pack launched

 

Intervet's Bovilis BVD vaccine is now available in a convenient 50-dose PET vial (100ml).This new, fully flexible pack is also fully compatible with Intervet's Eco-Matic vaccinator gun, ensuring consistent, accurate and efficient intramuscular dosing.

 

BVD is the UK's number one cause of abortion in dairy cattle and it remains a very costly disease to the industry. As a disease, it also causes immunosuppression that can make stock more susceptible to other diseases. And this is despite the relatively low cost of vaccinating of around £4 per cow, compared to the animal's value of perhaps £700 - £900.

 

Intervet's Bovilis BVD vaccine is well placed to help farmers control the disease, since it was developed from the UK's very own strain of BVD - strain C86. This gives it a very broad spectrum of control against the disease in the UK.

 

Detailed research into BVD has shown that many farmers are totally unaware of their herd's BVD status. This need not be the case since there are many relatively cheap tests available that can determine whether or not the disease is present, especially as we move into Phase 4 of the BVD Eradication Scheme from June 1, 2015.

 

Intervet offers two highly valuable diagnostic services to farmers through veterinary practices that use the company's vaccine, Bovilis BVD. DairyCheck and BeefCheck will very quickly and reliably determine the BVD and/or IBR status of a herd. The results will indicate if either disease is active and current in the herd, or whether there has been exposure within the last four to five years. Combining these results with the observations of other typical symptoms will help determine the best course of action, including vaccination if either disease is present.

 

Talk to Alistair at Parkside for more information of the new Bovilis BVD 50-dase pack, and the DairyCheck and BeefCheck diagnostic services.

 

Control strategies for two of the most widespread diseases in the UK - combination vaccine -

Two of the most prevalent, but frequently neglected, cattle diseases are BVD and IBR. National surveillance puts infection and exposure rates at 95% of all dairy cows for BVD and 50% IBR. 

 

Both BVD and IBR can be controlled with vaccination and then require stringent bio-security to maintain a herd's infection-free status. Even with vaccination in place, there have been cases of bought-in animals (possibly in-calf and infected) that have calved down with a BVD PI (Persistently Infected) calf, thereby bringing infection onto a farm. PI animals usually do not appear particularly ill for most of their lives, so the only way to keep your herd safe is by isolating and testing all new animals before introducing them to the rest of your herd. 

Around 30% of the national herd is now vaccinated against BVD and keeping a relatively closed herd and vaccinating replacements should protect you. However, anyone buying in animals, grazing them near other herds or concerned about higher than expected levels of abortion, poor fertility or above average calf pneumonia, should consider testing for BVD.

 

IBR control is a 'hot topic' in the vet world at the moment. In adult cows, acute infection is associated with a severe and prolonged drop in milk yield, reduced fertility and abortions. The virus is usually shed in secretions from the respiratory tract but can also be spread in the semen of infected bulls.

Once an animal has become infected it remains so for the rest of its life, despite the development of an effective immune response, and these animals can shed virus at any time when stressed, even if not displaying any symptoms. Movement of these asymptomatic but infected animals into a herd is often the source of new infections.

A recent international meeting of vets and other IBR experts organised by Intervet sought to understand IBR control options by examining how different countries have done this. The table below shows disease levels 10 years ago and, it is interesting to see that, since then, Scandinavia, Austria and some parts of Italy are now IBR-free and national eradication programmes now exist in Germany, Hungary, the Czech Republic and Slovakia.

Table 1: IBR prevalence in 1996

 

Country % of national herd affected

Hungary 80

Netherlands 70

Belgium 63

Italy 60

UK 50

Germany 50

Spain 25

France 10

Sweden 0

Finland 0

Austria 0

Denmark 0

Norway 0

Switzerland 0

 

The UK is not considering an eradication programme for IBR at present, but simply advises each farm to control the disease with vaccination. Anyone planning to re-enter the live export market, should research the IBR status of any market they plan to sell into, and discuss control strategies with their veterinary practice.