Publication - Advice and guidance
Bovine viral diarrhoea (BVD)
Advice on the requirements of Scotland’s BVD eradication scheme and details of the screening programme.
The Scottish BVD Eradication Scheme
The Scottish Government has committed to supporting an ambitious industry-led scheme to eradicating BVD from Scotland. The scheme has taken a phased approach and is currently in Phase 5. Read the guidance on Phase 5 requirements.
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 laboratory, and will set the herd status to BVD Negative or Not Negative. Results will be reported by the laboratory to the keeper and the Scottish Government
- A vet can change a herd status to BVD Negative provided that they have completed an online BVD training course and have sufficient evidence for 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 to of the disease reduce from 40% of herds having a BVD 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 cattle herds 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 the herd to find out if BVD is present. Instead, you can do a screening test that will show if the herd has been exposed to BVD. The result of the screening test will tell you and your vet whether the herd is 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
Breeding herds must update their herd status annually using one of the following BVD screening methods:
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.
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.
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.
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 take a sample of blood from not less than five animals that have been on the holding since birth in each separately managed group.
0. The dairy check-test - for year-round calving herds
The standard check test (option 1, above) 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. 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.
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.
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) that 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. If you are sampling calves under 20 days old, you must use an official id tag to take the BVD sample: this minimises the number of tags that are applied to a calf’s ear and reduces typographical errors at the BVD testing laboratory. Management tags can be used to take samples from other cattle (e.g. dead calves, older animals).
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, 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 tissue sampling tags you should minimise the number of tags applied to each animal. Applying additional ear tags can cause welfare problems for cattle.
If you decide to use tissue sampling 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
Mandatory testing methods for breeding herds with a long term 'not negative' status
Breeding herds that have been BVD Not Negative continuously for 15 months must undertake a Compulsory BVD Investigation (CBI) followed by a year of testing all calves. The CBI requires all animals in the herd to have a BVD status with 13 months. As soon as all animals have a BVD status and they are BVD Negative (i.e. any PIs have been removed from the herd) an Approved Vet must sign a CBI Completion Certificate and all calves born in the herd over the next 12 months must be tested for antigen(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. They are born BVD Positive and remain so for the rest of their lives. 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.
BVD Positive animals are only permitted to move directly to an abattoir, they cannot be moved for any other purpose except under licence from APHA. Licences are only issued for exceptional reasons, e.g. research purposes.
Herds that have a BVD Positive animal are BVD Positive and are restricted. Only BVD Negative animals can move out of the herd, and no animals can move in except under licence from APHA. Movement licences will only be issued in exceptional circumstances. BVD Positive herds will have their CPH listed on ScotEID’s PI locator, which is a biosecurity tool to alert cattle keepers to the presence of BVD in their parish. Keepers of BVD Positive animals have 40 days to retest and/or remove the animal from their herd before their CPH is listed on the PI locator.
Approved laboratories
Under the Bovine Viral Diarrhoea (Scotland) Order 2019, 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
Axiom Veterinary Laboratories Ltd
Biobest
Farmlab Diagnostics
National Milk Laboratories
SRUC
The Cattle Information Services (CIS)
Laboratory Approval
To gain approval, a laboratory must:
- 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.
- Be located in the European Union.
- 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.
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.
Phases of Scotland’s BVD eradication scheme
Phase 1: 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.
Phase 2: 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.
Phase 3: 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
Phase 4: 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
Phase 5: protect Negative herds at all costs
Controls introduced on 1 December 2019 include:
Movement restrictions on ‘Positive’ herds
- Introduction of the PI locator
- Introduction of the Compulsory BVD Investigation for herds that have been Not Negative continuously for 15 months
- Requirement to test high risk animals before they leave breeding herds
- If BVD positive animals are re-tested, the sample must be taken by a vet
- When tissue tagging calves under 20 days old, the sample must be taken using the official ID tag
Estimating the Savings to Farmers from Eradicating BVD
Scotland’s BVD eradication scheme was developed with the cattle industry to reduce disease and make Scotland’s national herd more productive. The Scottish Government have looked at the economics of BVD eradication and published the Estimating the Savings to Farmers from Eradicating BVD report in 2019. The report shows that the average-sized cattle herd will save £2,000 to £14,000 (depending on herd type) each year that the herd is BVD Negative.