From our overseas correspondent........

The 7th International Sheep Veterinary Congress took place in Stavanger, Norway in early June, a country that is home to 1 million breeding ewes with an average flock size of 67. With this relatively small national flock their approach to disease control is one of elimination and eradication which is driven and supported by their Government, but then there is no national debt in Norway. 

The Congress attracted high quality speakers from around the globe. One of the recurring topics was the management of Footrot and it was of interest to compare the differing approaches to this ubiquitous, debilitating condition in various parts of the world. 

Footrot has been a challenge to shepherds for as long as we have bred sheep. In an 1837 publication it was referred to as 'this dreadful and too frequent disease'

John Plant from Australia presented a paper on the eradication of virulent footrot from New South Wales. This ambitious program has been largely successful with 56 million sheep in 6000 infected flocks originally determined as infected in 1988 having been reduced down to just 26 infected flocks in 2008. The major reasons for the success of the scheme has been the commitment by the sheep industry in the State and the development of effective control and eradication programs for infected flocks. Key to their success has been that control is only attempted during periods when the causal bacteria cannot be spread i.e. during the dry season. He reported that if there was even so much as a drop of dew on the windscreen of the car on the morning of a control visit then the visit would be cancelled. This obviously presents limitations to any control program initiated in the UK. Otherwise their control programs were based on the correct use of vaccines to reduce the disease prevalence in individual flocks to a level where eradication could be achieved. Eradication programs were based on either culling all remaining infected sheep, with or without salvage antibiotic treatments. Field Vets played a role in the accurate diagnosis of virulent footrot by the clinical examination of a sufficient number of sheep in a flock.

Agnes Winter from the UK reported on the difficulties she encounters over here in our attempts to control footrot.

• Gathering pens, too little attention in the UK has been paid to the role of handling pens in the transmission of footrot. Dirty and badly maintained permanent pens with muddy approaches create more problems than they solve. Even if animals are footbathed, dirty pens beyond the footbath or turning out along muddy tracks will negate any beneficial effects. Gathering on dry days is beneficial. Additionally poor underfoot conditions that damage feet allow the bug to enter. The bug, Dichelobacter nodosus, can only cause disease in damaged feet or those affected by scald.
  
• Foot trimming routinely more than once a year is associated with a significantly higher prevalence of footrot. Trimming should only be used for diagnostic purposes, to remove obviously loose horn and to trim long toes. Excessive paring that causes bleeding must be avoided. The hoof trimmings themselves are a source of infection to other sheep so care must be taken to gather them up. The hoof shears also can spread infection so should be disinfected between sheep by plunging in a disinfectant, one that is changed regularly.
  
• Footbathing in 10% Zinc Sulphate is widely advocated but sheep must be allowed to stand in it and not just a gallop through. Foot baths should be big enough and long enough to facilitate this. Walk sheep through water or over stones/slats beforehand to clean the feet. Immediately afterwards they must be allowed to stand in a dry area for at least an hour to allow the chemical to dry onto the feet. The gathering of flocks for purposes unrelated to footcare, e.g. worming and drawing lambs for sale contributes to the spread so the use of a footbath after such procedures is beneficial.
  
• Vaccination can be curative as well as preventative. There is no long term immunity in sheep that have been infected so recurrence is likely. A vaccine developed in Australia, Footvax, has been used widely as part of a control program, with some success around the world. But as with any vaccine it is not a crutch to animal health and must be part of an overall management approach. Of the 19 different serotypes that cause footrot only 5 are contained within the vaccine. It was reported in some countries of them identifying the causal serotypes on a particular farm and then making up a vaccine to what they considered to be the 2 most important serogroups. This was reported to be successful. Vaccination is helpful in gaining control in heavily infected flocks but may need to be repeated at six-monthly intervals. The correct timing of repeat vaccinations is important prior to the main spread periods e.g. pre-housing.
  
• Use of clean pasture. As the survival time of the causal bug is limited to about 7 days, turning sheep after treatment on to pasture that has been sheep free for 10-14 days is beneficial after intense treatment of the group and separation of affected individuals.
  
• Use of clean pasture. As the survival time of the causal bug is limited to about 7 days, turning sheep after treatment on to pasture that has been sheep free for 10-14 days is beneficial after intense treatment of the group and separation of affected individuals.
  
• Quarantine. If you don't have it then don't introduce it and once you have got rid of it keep it out. Quarantine purchased sheep, footbathe them as above and closely inspect any lame sheep, vaccinate if entering an infected flock. If lame sheep appear consult Vet and treat group accordingly. Adequate quarantine is the most important point of prevention and must be taken seriously.
  
• Culling. Remove and cull animals which fail to respond to treatment. This is non negotiable even in pedigree flocks as there is a recognised genetic component to susceptibility.
  
• Breed for resistance. Work in this field is ongoing, but simplistically do not select replacements from footrot offenders once the condition is down to a manageable level.

Agnes Winter closed her keynote speech by stating that 'A combination of the measures described will be needed but the main commitment is to individual examination of each sheep to accurately identify infected animals, segregation and treatment of these and a willingness to cull non-responders. Careful monitoring of clean animals to ensure no infected ones have been missed is crucial and there needs to be recognition that the flock will be vulnerable to infection from purchased animals, strays or contaminated equipment, thus constant vigilance is required.

There are no shortcuts to controlling footrot as we are all too well aware with any infectious disease but experiences in the UK and down under show that with effort the results are rewarding from both a financial and importantly an animal welfare viewpoint.

To this end we will be holding a footrot workshop later in the summer to which all will be invited

 DT



' ...but then foot treatment is always going to be easier down under'