By Molly Morrison
Bovine Viral Diarrhoea (BVD) is one of the most significant cattle diseases in the UK, and it can be costly to your farm if left unmanaged. The challenge is that many infected animals show no obvious signs, yet the virus can spread rapidly through your herd.
BVD is a contagious viral disease caused by the Bovine Viral Diarrhoea Virus (BVDV), which affects cattle of all ages. It doesn’t just cause diarrhoea – it can lead to respiratory problems, poor growth, and most importantly, reproductive issues. The virus weakens the immune system, making animals more vulnerable to other infections. All of which results in lower productivity and reduced profits.
How Does BVD Spread?
The virus is mainly transmitted directly from infected to naïve cattle, often through airborne droplets when animals are close together. It enters through oral-nasal passages, eyes, or the reproductive tract. Indirect transmission is possible through fomites such as contaminated equipment, clothing, or wellies but is far less common.
Some cattle experience a transient infection (TI), meaning they pick up the virus, shed it for a short time, and then recover. These TI animals usually clear the virus within a few weeks and develop immunity, but during that shedding period they can still infect others.
The biggest culprits for spreading the virus are Persistently Infected (PI) animals. These form from vertical transmission of an infected dam to her foetus. Calves born to cows infected during early pregnancy (around 40–120 days). This is because the unborn calf’s immune system doesn’t recognise the virus as foreign allowing it to become a lifelong carrier. PI animals can shed large amounts of virus every day, infecting others without ever recovering themselves, therefore their identification is essential to eradicating the disease. See below how timing of infection of a cow during pregnancy affects calf outcome!
Routes of Entry into Your Herd
One PI animal can infect an entire herd, so good biosecurity is key!
Impact on Fertility:
This means longer calving intervals and fewer healthy calves!
Vaccination: Why and How
Vaccination is an insurance policy, reducing the risk of BVD entering your herd. Vaccinating will protect against the clinical effects of disease and reducing shedding in transiently infected animals, more importantly provide foetal protection preventing formation of a PI calves.
Options …
Two vaccines for BVD virus (BVDV) are licensed for use in the UK are Bovilis BVD and Bovela. Inactivated BVDV is also a component in three of the pneumonia vaccines: Bovalto Respi 4, Rispoval 3 and Rispoval 4.
Comparison:
Combine vaccination with testing and removing PI animals for the best results.
