Bovine viral diarrhoea
Also called BVD, mucosal disease
A viral disease of cattle whose main effect is to weaken the immune system. It causes fever, diarrhoea, abortion and calves that carry the virus for life and keep infecting the herd.
Cause and spread
- Cause
- Bovine viral diarrhoea virus (BVDV), a pestivirus.
- How it spreads
- Animals that are infected for life (persistently infected, born after infection of the mother in early pregnancy) shed large amounts of virus. Other animals catch it from them, and a short-term infection can also spread it.
Signs to watch for
- Fever, dullness, lower milk yield and diarrhoea in young cattle
- Weakened immunity, with more pneumonia and other infections
- Abortion, early embryo death and repeat breeding
- Calves born weak, with defects of the brain, eyes or coat
- Persistently infected calves that fail to thrive
- Mucosal disease: ulcers in the mouth and gut, nearly always fatal
Many diseases look alike. Only a laboratory test can tell them apart, so please see a veterinarian for any sick animal.
How it is diagnosed
Laboratory tests are needed, because the signs look like other diseases. PCR finds the virus in blood, serum or ear-notch samples, and is the way to find persistently infected animals. Antibody tests (ELISA) show exposure across the herd.
- Usually the first testBovine Viral Diarrhoea (BVD) PCRFinds the virus, including in carrier animals that look healthy.
- Supports the diagnosisBovine Viral Diarrhoea (BVD) Antibody ELISAShows whether animals have been exposed. Used for herd screening.
- Supports the diagnosisAbortion Panel (Brucellosis, Neospora, BVD) (panel)Looks at three common infectious causes of abortion together.
Prevention and control
- Find and remove persistently infected animals
- Improve biosecurity, test and quarantine new animals
- Test calves and aborting cows, and vaccinate the herd as advised by your veterinarian
Where this information comes from
- Bovine Viral Diarrhea and Mucosal Disease Complex · Merck Veterinary Manual
- Abortion in Cattle · Merck Veterinary Manual
General information for animal owners and veterinarians, last checked October 2026. It does not replace the advice of your veterinarian, who should decide which tests and treatment your animal needs.