WHAT IS FOOTROT?
Footrot is an infectious, contagious disease affecting sheep, goats and occasionally cattle. It can be costly and time consuming to control or eradicate.
Footrot exists as a spectrum of disease from benign footrot to virulent footrot.
Flocks infected with a benign strain see minimal impact, with it temporarily affecting the skin between the toes.
However, a more aggressive virulent strain can cause chronic lameness, ill-thrift, heavy production losses and, in some cases, mortalities.
The bacterium, Dichelobacter nodosus, thrives in moist, warm conditions and can survive up lo seven days away from the foot in favourable conditions.
Infection does not spread when conditions are hot and dry because the bacterium dies rapidly.
IMPACT
An outbreak of footrot can have damaging effects on the productivity and economic viability of a livestock enterprise, including:
- decrease in animal body weight, reducing ewe fertility and potentially increasing the need for supplementary feeding.
- lower lamb weights increasing mortality, health implications at weaning and reducing the value of prime lambs.
- lower wool production and quality, reducing fleece value.
- increased costs associated with the treatment or eradication of footrot.
- lower stocking rate from culling, and fewer marketing opportunities.
IS MY FLOCK SUSCEPTIBLE?
The expression and prevalence of footrot is affected by the virulence of the footrot bacteria strain, the environment and the type of sheep. Footrot generally spreads when:
- average daily temperatures are 10°C or higher for a number of days.
- there is sufficient pasture moisture to maintain wet feet.
The expression and spread of footrot increases during spring and sometimes autumn, depending on season and location.
Clinical signs of footrot vary depending on the virulence of the bacteria; a four-stage scoring system is used to describe the progression of an infection.
STAGES
Initial signs occur in the skin between the toes, with skin becoming red and hair falling out, and is given a score 1 or 2.
Score 3 sees the horn beginning to separate. A grey paste like substance will form at the site of infection, having a distinctive foul smell.
Severe infections can result in score 4, where the entire horny layer of the hoof can be separated.
MANAGEMENT
It is important to get a correct diagnosis of the strain before managing or eradicating footrot.
Benign footrot is usually controlled with foot-bathing. If infection occurs, reduce the spread and severity by:
- quarantining affected mobs so that clean sheep don't cross their path for 7 days.
- foot-bathing in zinc sulphate every 7-10 days or with RadicateR every 12-16 days.
- administer antibiotics prescribed by your vet, paying attention to withholding periods.
Highly effective, strain specific vaccines are available. To be effective, the specific strains on your farm have to be identified. Only two strains can be vaccinated for every 3 months; often 5% of sheep do not respond to the vaccine. Over the summer period, eradication is still advised for virulent strains.
ERADICATION
Successful eradication occurs when a plan is developed with your local sheep vet and an experienced accredited footrot contractor. It usually involves a combination of strategies including culling affected sheep over summer.
Virulent strains can be eradicated with a two-stage process that focuses on:
- managing spread of the disease over winter and spring to limit the damage caused.
- eradication over the no-spread period, summer.
PREVENTION
- Purchase sheep from clean flocks and examine feet for lesions, lameness and signs of treatment before purchase.
- Request a Sheep Health Statement stating the property's footrot status.
- When transporting stock ensure the truck is clean.
- Footbath sheep on arrival and quarantine them from other sheep until they have gone through an adequate spread period, usually the end of spring.
TAKE HOME MESSAGES:
- Find out what strain of footrot is present.
- Consult a sheep vet and accredited contractor to determine an a effective eradication plan.
- Footrot is a notifiable disease in Victoria so contact the local Animal Health Officer to help get back to normal production as quickly as possible.
- Reduce the chance of strays bringing in infection by ensuring boundary fences are sheep proof.
- Don't move sheep along roads that have been used by other sheep in the previous seven days.
LEGISLATION
Virulent footrot is a notifiable disease in Victoria which means:
- a livestock inspector must be notified of footrot outbreaks on your property.
- infected sheep must be sold direct to slaughter.
- it is illegal to place infected sheep in or near any public place including roads and saleyards.
- control measures must be implemented.
- livestock inspectors have the right to restrict the movement of infected or exposed sheep and to ensure suitable treatment options are undertaken.
For more information contact Stock Sense on 1300 020 163 or email stocksense@vff.org.au.
FURTHER LINKS
Meat & Livestock Australia
Coopers Animal Health
Author: VFF, original version published November 2012, updated March 2019. Disclaimer: The Victorian Farmers Federation (VFF), its partners, agents and contractors do not guarantee that this publication is without flaw and do not accept any liability whatsoever for any errors, defects or omissions in the information provided. This publication is intended for general information purposes only and does not constitute financial, legal, investment, production or marketing advice. The VFF excludes all liability for any loss or damage of any kind arising in relation to this publication including any reliance on the information contained herein.