Bovine viral diarrhoea

This guidance is for Wales

Bovine viral diarrhoea (BVD) can have very varied symptoms from inapparent infection to severe enteritis, abortion and death. It can have substantial impact on the profitability of farms. This highly contagious disease has been estimated to cost between £13 and £31 per cow in Great Britain. It impacts animal welfare within affected herds and reduces farm productivity and profitability.

Control and prevention can be achieved through improved biosecurity and vaccination.

Following pressure from the agricultural industry, the Welsh Government introduced legislation (the Bovine Viral Diarrhoea (Wales) Order 2024) with the aim of eradicating BVD in Wales.

Clinical signs

Clinical signs can vary greatly, such as a bout of diarrhoea or pneumonia (often in a group of animals), or an increase in abortions / stillbirths and a decrease in fertility and lower conception rates. BVD can also cause return to heat, embryo deaths, deformities and weak or premature calves.

Calves contracting the disease while still in the womb can be born as 'persistently infected' animals (PIs). Such animals continue to excrete the virus throughout their lives and are therefore the greatest risk of spread of infection. These animals, as well as failing to thrive, tend to have impaired immunity, making them more susceptible to other diseases. They are likely to die before reaching maturity. Cattle infected after birth can recover from BVD, but do suffer from a reduced ability to fight other infectious diseases.

BVD is spread via contact with infected cattle, particularly PIs. A thorough BVD testing regime, movement restrictions and good biosecurity controls are required to eradicate this disease.

BVD testing

As of 1 July 2024, all cattle keepers are required to annually test their herds for BVD.

Testing for BVD should be carried out by the following methods:

• mandatory annual BVD antibody screening method, where a number of unvaccinated calves or cattle are selected according to their age from each separately-managed group for testing. Your vet will be able to advise which animals to select for antibody testing. This will show if the herd has been exposed to BVD
• voluntary testing of newborn calves, by either blood sample or using ear tissue tags
• voluntary whole herd antigen testing, where all animals are either blood or tissue sampled

Ear tissue tagging is the only method you can do without the assistance of a vet.

Any blood samples must be taken by a veterinary surgeon and submitted to an approved laboratory.

The supporting assurance schemes, such as Red Tractor Dairy, already require farmers to have a BVD elimination plan in place or a CHECS accredited scheme. The Code of Practice for the Welfare of Livestock: Cattle (see paragraph 27) indicates that the written health and welfare plan should as a minimum cover specified diseases, of which BVD is one.

All herds enrolled under a CHECS scheme must declare the results of any screening carried out during the previous 12 months to either their own veterinary surgeon or a health scheme provider.

The route to establishing herd BVD-free status in a dairy herd is slightly different to that of a beef herd.

Herd status and movement restrictions

After the screening test, the herd status will be set to 'BVD negative' or 'BVD not negative'.

Herds with a status of 'BVD not negative' must undertake further testing of cattle to identify BVD-infected cattle. Keepers can retest a BVD-positive animal after 21 days of the initial test to find out if they are a PI animal or only a transiently infected animal. The retest must be done by a vet. Any animal that tests positive in two consecutive tests for BVD is also known as a 'PI animal'. The status of the herd can only change to 'BVD negative' when PIs are removed from the herd and BVD-positive animals are resolved.

From 1 July 2025, all herds with a status of 'BVD not negative' will be placed under movement restrictions. To move out of these herds, cattle will require a negative BVD pre-movement test, which is valid for 30 days.

Under CHECS, there are three standard programmes for BVD:

• Accredited Free (AF) Programme. Demonstrating that the herd is free from BVD
• Vaccinated Monitored Free (VMF) Programme. Demonstrating that BVD is controlled through vaccination of the breeding herd and by regular monitoring of young stock
• Eradication Programme. Implements a control programme to reduce the detrimental effects on herd productivity caused by the disease and to achieve freedom from the disease

To maintain the status, under CHECS, check tests are carried out on successive calf crops. Where animals have been confirmed as PI, they must not be sold on, except to slaughter. CHECS also requires movements off the farm to meet specified conditions, such as being kept separate from non-accredited cattle. The full requirements are detailed in the CHECS technical document (see link in 'Further information' below).

Minimising risk

PI animals are highly infectious and should be culled as soon as they are identified. PI animals must not be traded. Other cattle in the herd infected with BVD after birth are transiently infected and will normally recover.

As of 1 July 2024, PI animals are restricted on the farm for life. They must be:

• isolated from the rest of the herd
• housed indoors

BVD-positive and PI animals cannot be moved out of the herd unless direct to slaughter.

Keepers must disclose the BVD status of the herd and the individual animal before the purchase of the animal takes place.

Keepers buying cattle with an unknown BVD status and moving on to a Welsh holding will have to have the animal tested for BVD within 20 days of the movement.

Other means of reducing risk include:

• practise good biosecurity
• avoid buying in pregnant animals, as calves that contract BVD in the womb can become PIs for BVD. Also avoid taking pregnant animals to shows
• avoid nose-to-nose contact with cattle from neighbouring holdings
• vaccination may be an option, but this should be discussed with your vet

Can people catch the disease?

BVD is not known to affect humans, but good hygiene procedures should always be followed after contact with livestock.

Could it affect the food I eat?

No, it does not affect the food we eat and it cannot be contracted by consuming beef or dairy products.

Further information

The Welsh Government has published guidance on its new BVD eradication scheme. Guidance is also available from CHECS.

Trading Standards

For more information on the work of Trading Standards services - and the possible consequences of not abiding by the law - please see 'Trading Standards: powers, enforcement and penalties'.

In this update

No major changes.

Last reviewed / updated: October 2024