Publication - Advice and guidance

Bovine viral diarrhoea (BVD)

Published: 11 Feb 2019

Advice on what to do if you suspect there is an outbreak of this infectious disease and details of the screening programme.

Contents
Bovine viral diarrhoea (BVD)
Scottish BVD Eradication Scheme

The Scottish BVD Eradication Scheme

The Scottish Government has committed to supporting an ambitious industry-led scheme to eradicating BVD from Scotland. The plan is in four stages.

Stage one: subsidised screening

Stage one ran from September 2010 to April 2011. The Scottish Government provided £36 towards testing for BVD for each herd, and a further £72 towards further testing or veterinary advice if the result was positive. Around 4,000 herds took advantage, at a cost of £180,000.

Stage two: mandatory annual screening

All keepers of breeding cattle herds were required to screen their herds for BVD by 1 February 2013, and annually thereafter. A range of testing methods is available. Also, where there are calves born in non-breeding herds, they must be tested within 40 days.

Stage three: control measures (reducing the spread of infection)

In 2012, the Scottish Government consulted on proposals to introduce control measures, including movement restrictions. These control measures came in to force in January 2014, and include:

  • a ban on knowingly selling/moving cattle infected with BVDV
  • requiring the herd's BVD status to be declared before sale
  • restrictions on untested herds/animals

Stage four: enhanced testing and further movement restrictions

Controls introduced on 1 June 2015 include:

  • movement restrictions on 'not negative' herds
  • a reduction in the number of testing options available
  • the requirement to test replacement animals from untested herds
  • assumed negative status for dams of calves which have tested negative

Mandatory annual screening

All breeding herds are required to carry out screening for BVD annually

  • there are currently three acceptable screening methods to choose from
  • samples must be submitted to an approved laboratory
  • the result will be issued by the lab and give the herd a status of 'negative' or 'not-negative'. Results will be reported by labs to Scottish Government
  • a vet can change a herd status to 'negative', providing they have completed an online BVD training course and have sufficient evidence for the negative status 
  • all keepers of non-breeding herds must test any calves born for BVD virus within 40 days of birth

Since the introduction of the BVD eradication scheme, we have seen the level of exposure of the disease reduce from 40% of herds having a ‘not negative’ status. Evidence suggests that exposure to BVD in the beef herd is lower than in the dairy herd.

Minimum testing methods

Keepers of breeding herds of cattle in Scotland must have their herds screened every year for BVD. There are three testing options available. 

You do not have to individually test every animal in your herd to find out if you have BVD. Instead, you can do a screening test which will indicate if BVD may be present in your herd. Once you have done your screening test the result will tell you and your vet whether you are free of BVD or whether you need to do follow-up testing to find out if there is an active BVD infection in your herd. 

Your vet will be able to provide further advice about which method should be used and whether it is appropriate to test for antibodies to BVD or BVD antigen/virus in your case. You must use one of the following methods:

Mandatory annual screening methods for breeding herds

0. The dairy check-test - for year-round calving 'negative' herds

The standard check test is appropriate for herds that have distinct block calving periods. In dairy herds that calve all year round it can be difficult to ensure that the heifer groups are surveyed properly. To ensure that exposure is detected in these herds more animals must be sampled more frequently. 

If you have a dairy herd that calves all year round, your vet should blood sample no less than 10 calves between the ages of 9-18 months, the five youngest and five oldest unvaccinated cattle within each group. This test must be carried out twice per year, roughly six months apart; more than seven months apart will indicate an expired test result. If you have a dairy herd that calves in distinct seasons you can use the normal check test providing all separate groups are tested.

The number 0 has been allocated for the dairy test in order that the database can recognise that the dairy check-test has been used.

1. The check-test

Whenever possible for a check test, use option (a) below. Where this is not possible options (b) and (c) should be followed in order. All of these three tests are for antibody, and show if the herd has been exposed to BVD.

Before deciding to do a check test, speak to your vet to identify how many separately managed groups you have in your herd. Your vet will decide how many animals need to be blood tested.

(a) Five calves aged 9 to 18 months

Your vet should take samples of blood from not less than five calves in the age range 9 to 18 months in each separately managed group. If there are fewer than five calves in a group, then test all the calves in the group.

(b) Ten calves aged 6 - 18 months

If any of your sample of calves are aged 6-9 months, then your vet should take a sample of blood from not less than ten calves in the age range 6-18 months in each separately managed group.  If there are fewer than ten calves in a group, then test all the calves in the group.

Shetland only: in recognition of the successful eradication of BVD from Shetland, your vet may take blood from not less than five animals in the age range 6-18 months. If there are fewer than five calves in a group, then test all the calves in the group.
(c) Five over 18 months and on the holding since birth

If you have no calves in either of the above age categories, but only then, can you choose to use the following method:

Your vet should ake a sample of blood from not less than five animals that have been on the holding since birth in each separately managed group. 

Mandatory testing methods for breeding herds with a 'not negative' status

2. Calf screen - test all calves

Individually test all calves born in the herd in the past year for virus by blood or tissue sample. You can test the calves as they are born or all at once. Ear tissue tag testing (explained below) can be a particularly useful way to do this and is the only method, apart from 'method 3: test all animals' (detailed below) which you may do without the assistance of a vet.

Ear tissue tags

Ear tissue sampling tags are designed to take a tissue sample from the ear whilst tagging the animal. The tissue goes into the labelled capsule when the animal is tagged, which you then snap off and send to the laboratory.

If you want to purchase ear tissue sampling tags then contact your usual ear tag supplier. If they do not stock them they should be able to direct you to somewhere that does.

3. Whole herd screen - test all animals in the herd

Individually blood or tissue sample all the animals in the herd at the time of sampling. This is a test for virus and has the advantage that all the persistently infected (PI) animals in the herd can be identified and removed. The farmer may choose to tissue tag everything, in which case a vet does not need to be consulted, however, if they choose to take blood samples a vet will need to be involved. If all the animals are negative for BVD virus this will constitute a negative result for that year.

This testing method is the most expensive option, but it may suit herds where BVD infection is suspected or herds where no other method is entirely suitable.

Important welfare note on ear tagging

If you wish to use ear tissue tags you should, if possible, use those that are also the official ID tags, either primary or secondary. Applying additional ear tags can cause welfare problems for cattle.

If you decide to use ear tissue tags, make sure you use the correct applicator – some may appear to work with other tags but can apply them too tightly, causing pain and leading to infection.

Testing options summary table:

No Testing option Dairy/Beef Test for antibody/antigen (virus)
0 Dairy with year-round calving
10 animals 9-18 months twice a year
Dairy Antibody
1a 5 animals between 9-18 months per separately managed group Either Antibody
1b 10 animals between 6-18 months per separately managed group
Shetland only: test five animals from this age range
Either Antibody
1c If neither above are possible - 5 animals 18 months+ on holding since birth per separately managed group Either Antibody
2 Calf screen Either Antigen (virus)
3 Whole herd screen Either Antigen (virus)

Antibody: tests for exposure to the virus
Antigen (virus): tests for the presence of virus

Persistently infected cattle (PIs)

Cows that get infected with BVD in their first four months of pregnancy can give birth to a persistently infected (PI) calf. These PI animals are the major source of BVD infection, as they will have the virus all of their lives and spread it in huge quantities. Many will die within the first year of life, but some can live much longer and may appear normal. Cattle infected with BVD after birth are transiently infected and will normally recover in around four weeks, but do suffer from a reduced ability to fight other infectious disease and are likely to have impaired fertility until they recover.

Approved laboratories

Under the Bovine Viral Diarrhoea (Scotland) Order 2013 (as amended), samples submitted for testing as a mandatory annual screening test must be sent to a laboratory approved by the Scottish Government for that purpose.

To submit a sample to an approved laboratory, please use a form provided by them or the standard submission forms (vet and farmer use).

Agri-food and Biosciences Institute
APHA
Biobest
Farmlab Diagnostics
National Milk Laboratories
SRUC
The Cattle Information Services (CIS)

Laboratory Approval

To gain approval, a laboratory must:

  1.  Hold a current accreditation of ISO17025 from an organisation that is itself accredited to ISO 17011 (EN 45002/3) for testing for BVD antigen and/or antibody.
  2.  Be located in the European Union.
  3.  Agree to meet the duties of approved laboratories as described below.

Duties on Approved Laboratories

The laboratory must test samples submitted under the Order within five days of receiving the samples.

The laboratory must declare a status for the samples submitted. This will be based on the test results generated by the samples submitted and other information provided, such as vaccination history. The status will be either:

  • negative for evidence of BVDV infection;

 or, if  the above status cannot be given,

  • not-negative for evidence of BVDV infection.

Laboratories will use their professional judgement in reaching a decision on herd status. They may request such information as they reasonably require of the person submitting the samples in order to reach a herd status. Where insufficient information is supplied in spite of such a request being made, the laboratory may withhold a declaration, or declare a not-negative status.

The laboratory must inform the keeper of the herd status.

Laboratories may charge their customers at whatever level they decide, and at different levels for different types of test. Fee levels for all types of test should be published on the laboratory’s website.

Laboratories must electronically submit herd status data to ScotEID, the central BVD database, together with the individual official cattle ID numbers for each animal tested, the test type and the result from each sample.

Cattle that test positive will be presumed to be persistently infected (PI) until proved otherwise by a future test, or unless a vet can declare with confidence that the result suggests transient infection.

Laboratories must keep records for at least three years. The Scottish Government may request access for themselves or specify that it be given to research providers on their behalf.