Changes to the management of footrot in South Australia were introduced in July 2018.
Changes to the program that producers should note:
- National Vendor Declarations (NVDs) and National Sheep Health Declarations (NSHDs) are still compulsory.
- The new July 2019 version of the NSHD requires declaration of all forms of footrot both benign and virulent.
- Laboratory based diagnosis will be the primary method used to classify the severity of footrot detected in a flock.
- There will be increased ability for infected producers to trade sheep based on their flock’s diagnosis. Buyer beware means you need to check the status of animals BEFORE you purchase – check the NVD and NSHD. Movement restrictions into SA remain in place.
What is footrot
Footrot is a contagious bacterial disease in sheep. Footrot is classified as inflammation of the interdigital skin and potential under-running of the hoof caused by the bacteria Dichelobacter nodosus (D. nodosus)
It can cause significant economic loss to producers through reducing:
- ewe fertility
- wool growth
- growth rates
- sheep sales.
Controlling or eradicating footrot can be costly however the long term benefit of eradicating footrot from a flock far outweighs the cost.
Footrot is a notifiable disease and suspicion of any form of footrot must be reported immediately. See the reporting animal disease page for instructions.
Development of Footrot
Like all diseases, there are three main factors that affect the development and severity of footrot in a flock, they are:
- Agent – In the case of footrot this is the bacteria D nodosus and the potential virulence of the strain of D. nodosus present in the flock.
- Host – How susceptible the sheep in the flock are, some breeds are more susceptible to footrot than others. No breeds of sheep are resistant to footrot.
- Environment – Footrot requires warm moist conditions to develop and adequate pasture length to enable transmission of the bacteria from sheep to sheep.
Diagnosis of Footrot
There are two main ways to diagnose footrot in a flock and both require inspection of a significant number of sheep:
- Clinical Diagnosis – Where it is possible to inspect sheep during a “spread period” (warm, moist with adequate pasture length) hooves can be inspected and pared to reveal the most severely affected sheep in the flock. The percentage of sheep suffering severe footrot lesions can then be used to form a diagnosis of benign or virulent footrot.
- Laboratory based diagnosis – Often, the time of year, current climate and other management factors do not allow for an accurate clinical diagnosis, especially during dry times or in traditionally drier parts of the state. For this reason the South Australian Footrot Management program utilises a laboratory test called the “Elastase Test” to assign a flock diagnosis. By submitting samples from multiple infected sheep across the flock, the Elastase test can return results which indicate how severe a footrot infection may be under ideal development conditions.
When a flock has footrot
If a flock has been detected with footrot there are movement restrictions that apply under the South Australian Livestock Act 1997.
When there is a suspicion a flock has severe virulent footrot, sheep:
- cannot be sold to other graziers
- must not be sold in a public market
- must not be allowed to stray onto public roads or neighboring properties.
Sheep with footrot can be sold directly to an abattoir for slaughter.
Specific trading options will be assigned to all flocks detected with footrot in South Australia, those options may vary depending on the severity of footrot diagnosed.
Footrot detection trial underway
Biosecurity SA is speeding up the detection of footrot through a statewide 12 month trial into the cutting edge loop mediated isothermal amplification or LAMP diagnostic process. LAMP is a portable diagnostic technology that uses a single tube technique for the amplification of DNA.
LAMP is an on-farm test that can give a diagnosis within 20 to 30 minutes. Results from currently available laboratory test processes can take several weeks.
As part of the trial, Biosecurity SA Animal Health officers will compare the LAMP process to other existing disease technologies.
While this current trial focuses on footrot LAMP can also be used for other animal and plant disease detection, depending on the availability of suitable reagents.
For further information contact Chris van Dissel on 85 686 415 or your local Animal Health Officer.