Bovine pestivirus or bovine viral diarrhoea virus (BVDV) and mucosal disease in cattle

Adapted from Western Australia Department of Agriculture 

Bovine pestivirus or Bovine Viral Diarrhoea (BVDV) are the same disease – different people call the different things. We will call it BVDV in this article. BVDV is one of the most complicated cattle diseases we deal with. Don’t worry if you need to ask or read articles a few times to understand the disease. We often do as well.

BVDV can be a serious threat to beef farm production and profitability. This article, some of which comes from the Western Australian Department of Agriculture, explains the effect of BVDV on different groups of animals.

What happens when BVDV occurs?

The effect of BVDV depends on whether it occurs in unborn calves, pregnant cows, feedlot or other cattle.

Unborn calves

• Most of the harm done by BVDV is to unborn calves and depends upon timing of infection.
• Infection of a naïve cow (one notpreviously been exposed to or vaccinated for BVDV) in early pregnancy causes loss of the embryo.
• Infection of naïve cows in mid-pregnancy can cause abortions, birth defects and live-born calves to be persistently infected with BVDV. These calves spread the disease within and between herds. Most of these calves die within two years of mucosal disease.
• By the last third of pregnancy, the calf has developed sufficiently to produce immunity. Some of these calves may be aborted, but most are born healthy.

Pregnant cows

Infection of a naïve cow results in a mild 2–3 week illness that suppresses the cow’s immune system and reduces disease resistance. Most important are the effects on her unborn calf noted above. After recovery these cattle are immune to BVDV.

Feedlot cattle

If a persistently infected animal is introduced to a feedlot, infection will spread to all naive cattle in that pen and adjoining pens within days. It will rarely spread further because usually only persistently infected animals shed an infective dose.

The exposed naïve cattle will develop mild illness and suppressed immunity. As this coincides with transport and social stress, diet change and challenge by other diseases, the health impact of BVDV in affected pens can be significant.

All other cattle

Other cattle exposed to BVDV will also experience a 2–3 week illness followed by lasting immunity. Exposing non-pregnant cattle to persistently infected animals can stimulate immunity and protect future pregnancies in those cattle.

Table 1 What immunity status definitions mean

Table 2 Effect of BVDV infection on cattle according to pregnancy status

Table 3 Signs of BVDV