Sheep showing signs of footrot
A four-year study across a total of 39 sheep flocks by the Universities
of Bristol and Warwick has confirmed that the currently available
footrot vaccine covers the D. nodosus strains causing footrot in
England and Wales.
The vaccine available to UK sheep farmers originates from Australia
and contains ten strains of D. nodosus known to cause footrot.
However, this latest study - recently published in the journal
of Veterinary Microbiology - confirms that the D.nodosus strains
causing lameness problems for flocks in England and Wales are the
same as those in Australia.
Commenting on the study findings, Schering-Plough veterinary adviser
Paul Williams says sheep producers in this country can be confident
in the efficacy of the Footvax vaccine for flocks where footrot
has been confirmed as the cause of lameness problems.
"For vaccination to be effective it is important that producers
have a definitive diagnosis of footrot, as opposed to any other
lameness condition such as CODD or scald. It is important to recognise
that CODD or scald are different conditions and cannot be controlled
by vaccination," he stresses.
"If true footrot is the cause of lameness, the only way to
break the disease cycle is to undertake a whole flock control programme."
Paul Williams says that the 'best practice' control programme
starts by vaccinating and footbathing all sheep, then splitting
the flock into two groups: those sheep that are obviously infected
and those which are not infected. "This simplifies the treatment
regime, reduces the disease challenge for uninfected sheep and
helps identify those animals not responding to treatment for culling," he
"Infected sheep should be given an antibiotic injection and
walked through a footbath every five days. After three footbath
treatments, any sheep that have not responded should be considered
for culling. Uninfected sheep should be footbathed and moved onto
clean grazing. If it is not practical to segregate uninfected and
infected sheep, make sure all the animals are footbathed - again
every five days," he says.
He recommends that annual vaccination should be a central part
of the programme for all sheep that face a footrot challenge, with
additional booster doses being used to treat infected animals.
"Vaccination with Footvax provides effective treatment for
infected sheep, as well as long-term protection. A single injection
of the vaccine can be used to treat footrot because antibodies
are produced against D.nodosus. Sheep do not produce a natural
antibody response to D.nodosus, which means they will never develop
a natural immunity to footrot so will remain susceptible year after
year. This is why vaccination is so important.
"An initial 1ml injection will stimulate adequate antibody
response to treat existing infections and prevent new ones for
up to five months. But it is advisable to vaccinate again four
to six weeks later for improved cure rates and longer on-going
protection. Thereafter, an annual booster should be sufficient
to keep footrot at a manageable level," he advises.
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