We often forget footrot is an infectious disease
We often forget footrot is an infectious disease, this explains why bringing the ewes into the pens for a day’s trimming and foot bathing then running them through the same mud they walked in from is not likely to be effective. Rate of spread depends on level of challenge, which is a product of the number of infected feet in the flock and duration of exposure. We now think severity is due to the level of the challenge disease not just the presence as some sheep will have a degree of immunity.
Listing treatments in decreasing order of their effectiveness ie the time taken for healing, is shown in the table below.
Product/Treatment Estimated Time To Healing
Long acting antibiotic injection 2 days
Trim and antibiotic spray 9 days
By far the most effective treatment is the long action antibiotic injection as it removed the challenges.
Vaccination is also very effective as it too reduces the number of lame sheep and the level of challenge.
National infection levels at around 10% of sheep affected has a huge effect on productivity and shows we are not making a good job of control on most farms. In a survey it was found that farmers who were willing to catch any lame ewe in the flock and treat them immediately had around 5% footrot, those waiting a few days until there was a group needing treatment had around 10% lame and those who did not make it a policy of catching lame sheep and were just dependant on foot bathing and trimming had around 17% infected.
So it is clear that to control footrot you need effective treatments like an antibiotic injection that when applied in the field cures the sheep quickly and reduces spread. Alternatively if the problem is too big for this approach and you bring the whole flock in them in for a less costly flock treatment such as footbathing then it is important that any infected sheep identified are kept away from the rest of the flock, and that the flock is returned to a fresh field, without getting infected on the way. This reduces the rate of spread, which is always highest in warm wet weather.
Tips To Reduce Footrot This Summer
• Make it a policy to check feet in individual pens at lambing and not to turnout ewes into the main groups that have footrot.
• Give them a long lasting action antibiotic injection and put them into a separate hospital group close to the pens where they can be run through the footbath until problems are resolved.
• Antibiotic treatment of lame sheep, caught in the field can keep on top of a low incidence problem •
If possible pull out ewes and their lambs for treatment if handling in early summer while the numbers are still readable on the lambs, isolate ewes and if they do not respond to antibiotic injection mark then for culling at weaning.
• If the main mob shows signs of footrot, particularly in lambs, put them through a footbath of 3% formalin and let them stand on concrete for one hour to reduce spread. This has to be done immediately the first symptoms are seen – not a few days later as this delay can lead to the difference between success and failure.
• Take every opportunity to sort out infected sheep from sound sheep, eg at housing or shearing and treat infected sheep in a separate group.
John Vipond, SAC Sheep Specialist
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