BVD is a serious disease of cattle in terms of economic cost, health and welfare, causing abortion, infertility, immunosuppression, failure to thrive and even death.
BVD causes a complex of diseases in cattle, the most important of which can interfere with reproduction, affect the unborn calf and lead to mucosal disease. BVD virus can also cause enteritis during acute or transient infection which is usually mild but occasionally severe enough to cause death, even in adult cattle. Transient BVD virus infection is associated with significant suppression of disease resistance and can contribute to outbreaks of pneumonia or scours in calves, and other diseases.
The disease is mainly spread by persistently infected, or PI, cattle. These are born with the disease, having come into contact with the virus in the womb during the first 120 days of gestation. They will have BVD all their lives and they shed virus extensively, infecting naive cattle directly and indirectly. Most die as calves but a few live much longer. Identifying and removing them from the national herd is critical to any eradication attempt.
Protect your herd from BVD
BVD is spread easily and quickly by PIs (persistently infected cattle). The focus of Scotland’s BVD eradication scheme is to find all PIs and then to prevent them from infecting other cattle. We know from other national programmes that if all the PIs are removed, BVD can be eradicated.
Infection can spread by other routes, but these are much less important than PIs in keeping disease circulating. The other routes for spreading BVD are:
- transiently infected cattle, which produce less virus than PIs and only for 2-3 weeks and
- contaminated surfaces; you can transport virus on dirty hands, clothing, vehicles and equipment
To protect your herd from BVD infection, firstly prevent contact with PIs and transiently infected animals. The risk can come from within your herd, from neighbouring herds over the fence, cattle in the same show ring, the next pen at the market or inside the same vehicle. Secondly, reduce the risk of bringing virus on to the farm via contaminated surfaces. Good hygiene applies to all visitors to the farm, as well as to the keeper and any farm staff.
Protective measures to consider:
- breeding herds must update their BVD herd status annually, and should investigate any signs of infection. Your vet will be able to advise you
- careful sourcing of replacement cattle: if in doubt check the animal’s individual status before buying. ScotEID’s BVD lookup is quick and easy to use
- “trojan cows”: take extra care if you are bringing in-calf cows or heifers in to your herd. The unborn calf may not have the same BVD status as its mother and cannot be BVD tested until it is born. If unprotected females were exposed to BVD early in pregnancy, the calf will be a PI. If you have purchased an in-calf cow or heifer, calve her in isolation and test the calf for BVD virus as soon as possible. Tissue tagging allows a test for BVD virus at the earliest possible age. Don’t allow the calf to have contact with other cattle until it has a BVD negative test result
- markets: all livestock markets in Scotland have access to ScotEID and should be able to tell you the BVD status of the animal you intend to buy. Some of the markets in Northern England also have access to ScotEID. Where Scottish markets are selling breeding stock, they have an obligation to tell buyers the BVD status of the animal. Remember that some diseases, including BVD, can spread easily between pens at a market and consider keeping newly-purchased cattle away from the rest of the herd for the first couple of weeks
- BVD vaccination can reduce risk of infection entering the herd: your vet will be able to advise
- double-fencing can stop contact with neighbouring cattle
- shows: show cattle can catch BVD from others at the event. Some PIs look healthy and if you are very unlucky, cattle in the same class as yours may be carrying the infection. Consider vaccinating your show animals before the show season; your vet will be able to advise
- transport: PIs can be taken directly to slaughter. When a transporter is doing multiple pick-ups of slaughter animals, the PIs must not be unloaded at any of the interim premises before arrival at the slaughterhouse. Ideally, any animals that are known to be BVD positive (PIs or suspect PIs) should be the last animals of a multiple pick-up round. If an emergency arises and BVD positive animals must be unloaded, they must not be allowed to come in to contact with cattle other than those that are also travelling to slaughter. If they have to be unloaded, it is advisable to clean and disinfect any area where BVD positive animals have been before other cattle use the same hard standing or equipment
The principle BVD order is The Bovine Viral Diarrhoea (Scotland) Order 2019 which sets out the main requirements of the BVD eradication scheme in Scotland.