printStock Journal article - December 2025
Author: Dr Jim Walsh, Coopers Animal Health
Footrot is an infectious disease of sheep, occurring throughout Australia but is most prevalent in the medium to high rainfall areas. Dichelobacter nodosus is the bacteria which causes footrot which thrives in moist, warm conditions.
The footrot bacteria need the hooves of infected sheep to survive, and can survive indefinitely in pockets of infection inside the feet of infected animals, even under dry conditions. However, the bacteria cannot survive for more than 14 days in soil.
There are many strains of the footrot bacteria which vary in their ability to cause disease.
Severity of footrot depends on three factors:
- Strain of footrot bacteria: Benign strains never cause severe disease. In contrast, highly virulent strains will cause severe disease when the environment favours their spread and development in feet.
- Sheep factors: Some breeds of sheep are more resistant to footrot than others. For example, British breed sheep are not as predisposed to having badly affected feet even when infected with virulent strains of footrot. In contrast, Merinos tend to be badly affected when infected with virulent strains. Even within the one breed of sheep, some sheep are more resistant to footrot than others.
- Environmental factors: Moisture and temperature are important factors affecting the transmission and expression of footrot. Footrot will not spread under hot, dry conditions. The main footrot spread period is during wet autumns, mild winters and spring.
Lameness is often the first sign of footrot. There are several other conditions which cause lameness, which means it is essential to make a proper diagnosis. An incorrect diagnosis may lead to substantial economic losses due to inappropriate management.
Footrot diagnosis can be difficult. Seek expert advice from your local PIRSA Animal Health Officer.
While eradication programs can vary from farm to farm to suit individual needs, they all have four basic stages:
- Planning: There is no point in attempting an expensive eradication program if your sheep are quickly re-exposed to infected sheep. Considerations to biosecurity must be made. A good plan includes understanding and consideration of the farm’s facilities as well as the management, flock structure, labour and finances required to control footrot.
- Control: Footrot needs to be controlled during the spread period so that the infection in the flock is reduced to a level where eradication is feasible. The aim of control is twofold. Firstly, to have as few infected sheep as possible at the start of the eradication stage.
Secondly, control is necessary to prevent production losses and for the welfare of the sheep. Control during a spread phase is achieved by either vaccination or regular footbathing or a combination of both. The choice between control methods is very complex so seek expert advice. Information on vaccination options and best practice will follow in a later article. - Eradication: The aim of the eradication phase is to identify and remove all the remaining infected sheep from the flock when footrot is not spreading. Removing all infected sheep prevents them reinfecting the clean sheep during the next spread period (warm and wet weather).
- Surveillance and Biosecurity focus: Surveillance and monitoring are essential once a mob has gone through the intensive control and eradication program to ensure footrot has been eradicated and good biosecurity practices implemented to prevent reinfection.