Bovine Viral Diarrhoea in Cattle

Bovine viral diarrhoea is a highly infectious disease that infected animals transmit through the virus. According to Animal Health Ireland, BVD costs Irish herds €102 million annually.

The National Eradication Scheme identified 13,995 persistently infected (PI) BVD animals in Ireland in 2013. The following year, over 9,500 calves were found to be persistently infected. Ireland has made notable progress toward eradicating BVD, thanks to the implementation of a compulsory eradication programme.

Ear notch testing results from 2016 show that 99.2% of calves tested negative for the BVD virus. However, 4,510 PI BVD calves were born in 2016, spread across over 2,500 herds throughout the country.

How Bovine Viral Diarrhoea Spreads Among Cattle

Bovine Viral Diarrhoea mainly spreads through nose-to-nose contact between infected cattle within the herd. Contact with infected animals from neighbouring farms, at marts or shows, and during transport also facilitates its spread. In addition, exposure to contaminated equipment, other species like sheep, or visitors to the farm can infect animals.

What is a persistently infected (PI) animal?

Persistent infection occurs when a dam becomes infected with BVD for the first time during the first 4 months of pregnancy. Her developing calf becomes persistently infected with the virus and sheds high levels of the virus thereafter. Persistently infected animals (PIs) may appear normal but remain a significant source of infection on farms. PIs test virus-positive at all times. If PI cows become pregnant, they will give birth to PI calves.

What is a transiently infected (TI) animal?

Acute or transient infection occurs when an animal becomes infected at any time after birth. Often, this infection does not show obvious signs. When animals contract BVD, their immune system recognizes the disease and produces antibodies in response. Transiently infected (TI) animals test virus positive at the time of infection but become virus negative within 3 weeks after infection. Once TI animals clear the virus, they no longer pose a threat to the rest of the herd. Most PI animals are born to cows that contracted BVD during the first 4 months of pregnancy. Hence, it is crucial to protect dams against infection during pregnancy through vaccination.

Why do I need to vaccinate if I am testing all calves and removing PI’s?

Removing PI animals will reduce the amount of virus circulating within the herd. However, transiently infected animals can continue to spread the virus, even after a PI animal has been removed. If cows are not protected during pregnancy, transient infection during the first 4 months can lead to the birth of future PI calves. The most effective approach to BVD control within the herd is to test and eradicate PI carriers, vaccinate to protect pregnant cows, and be vigilant regarding biosecurity. Herds that retain PI animals pose a significant threat to neighbouring herds’ disease control.

Why do I need to vaccinate if I am testing all calves and removing PI’s?

BVD control is based on 4 pillars

1. Remove PI’s from herd
2. Maintain a high level of biosecurity
3. Monitor your herd to ensure it stays clear of circulating virus
4. Vaccinate with Bovilis BVD

Removal of carrier animals as soon as possible after identification is essential if a herd is to become clear of disease. Monitoring purchased stock for the presence of the virus helps prevent the purchase of carrier animals. Given the high risk of infection in this country, we must ensure that animals are protected until BVD is eradicated. Vaccinating cows and heifers before each breeding season helps protect against the effects of BVD infection during pregnancy.

Protecting the Foetus from Bovine Viral Diarrhoea

After identifying and removing PIs, it is essential to take steps to prevent the BVD virus from re-entering the breeding herd. The country’s high cattle movements and generally sub-optimal biosecurity make vaccination a critical part of disease control. Since PIs are the result of foetal infection in early gestation, the aim of vaccination is to ensure maximum immunity levels at this stage, thereby protecting the foetus from transplacental infection. Bovilis BVD provides 12-month foetal protection.*

BVD Vaccination Programme for Cattle

Bovilis BVD protects the foetus from BVD virus infection via the placenta in cows and heifers from 8 months old. A primary vaccination course, commencing after 8 months of age, requires 2 doses of Bovilis BVD given by intramuscular injection four weeks apart. Ideally, complete the vaccination course a month before the start of the breeding season. Booster vaccination in following seasons requires a single dose of Bovilis BVD 4 weeks before the start of the next pregnancy. You can conveniently administer Leptavoid H at the same time as Bovilis BVD to cows and heifers, thereby protecting against both BVD and leptospirosis.

Farmers can combine Bovilis BVD and Bovilis IBR Marker Live vaccines as a booster dose for cattle from 15 months old. Use Bovilis BVD and Bovilis IBR Marker Live separately when administering the primary vaccine against BVD and IBR. You can mix these vaccines together and administer them in a single 2ml intramuscular injection for booster doses. Less crush time means less stress on man and beast!

*One vaccination 6 months after basic vaccination course with next re-vaccination at an interval no greater than 12 months.

Product Focus

Bovilis® BVD

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“Animal Health Ireland estimate the annual cost of BVD to Irish herds totals €102 million.”