What to look for

Animals are usually found dead
If animals are observed before death they may:     

  • Be very depressed and have a high fever 
  • Have difficulty walking 
  • Have swelling in the major muscles of the leg or neck 
  • Have pockets of gas that may be felt in the affected tissues



A bacterial infection (Clostridium chauvoei). This bacteria is widespread and can form highly resistant spores that persist in the environment. Animals pick up the bacteria from pasture and it lodges in their muscle tissues. If the muscle is wounded or bruised, this triggers the organism to start to proliferate and produce a lethal toxin.

Animals likely to be affected

Cattle 6-24 months of age, grazing on good quality pastures and in good condition.

Other diseases with similar signs

Enterotoxaemia, bloat, anthraxgrass tetany or some types of poisoning.

Confirming the diagnosis

Changes in muscle tissue at post-mortem.

Spread of the disease

Not spread from animal to animal. Several animals may be affected at the same time which may mean they have had a common exposure to the same trigger from handling or transport.

Risks to people

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


Usually too late to treat. The most effective action is to remove the herd to another paddock and to vaccinate all stock against the common Clostridial diseases.

Risk factors

  • Failure to vaccinate young stock
  • Rough handling of stock in yards or during transport


Give “5 in 1”, “7 in 1” or “8 in 1” clostridial vaccine according to the label recommendations.


Do you want animal health info delivered?

Subscribe to Dairy Australia publications