Black disease

What to look for

  • Animals are often found dead
  • If seen before death, animals are depressed, have reduced milk production and are not eating. After death, the animal carcase decomposes quickly, may have bloody discharges from the mouth and nose and sometimes appears black.


Cause - a bacterium (Clostridium novyi) + liver damage

Clostridium novyi is commonly found in soil and persists as very resistant spores. When eaten by cattle it enters the body and lodges harmlessly in the liver. If the liver is damaged it may trigger the organism to multiply and produce a fatal toxin. Liver damage is usually caused by immature fluke burrowing through the liver, so black disease generally occurs in summer and autumn when cattle are exposed to fluke infestations.

Animals likely to be affected

Black disease is unusual in cattle and more often seen in sheep. It usually occurs in cattle grazing damp areas.

Other diseases with similar signs

Can be confused with other causes of sudden death such as anthrax, grass tetany, blackleg, enterotoxaemia.

Confirming the diagnosis

Post mortem examination of the liver. Your vet can take samples for laboratory testing. The typical history is of sudden death of one or more animals, the farm being in a liver fluke area and animals not being vaccinated.

Spread of the disease

A number of animals may be affected but the disease does not spread from animal to animal.

Risks to people

While black disease is not a risk to people, there are other causes of sudden death in cattle, such as anthrax, which can cause serious human disease. Carcases of dead animals should always be handled with care, using protective clothing and good personal hygiene. Call your vet if you are unsure about the cause of death.


If animals are found in an early stage of the disease they may respond to antibiotics.

Risk factors

  • Failure to vaccinate stock with Clostridial vaccines that include black disease
  • Failure to control liver fluke