Most outbreaks of lameness in sheep are caused by either
interdigital dermatitis (scald) or footrot; footrot is responsible
for 90 per cent of sheep lameness. Interdigital dermatitis
and footrot are caused by the bacterium Dichelobacter
nodosus. The UK's temperate climate provides an ideal
environment for transmission of the bacterium that causes
footrot. The important risk factors for foot lameness are
damage to the interdigital skin by exposure to moisture and
mechanical trauma, and transmission of D. nodosus from infected
sheep. Other risk factors include movement of sheep onto the farm
without effective quarantine and perimeter fences that are not
Fig 1 Many outbreaks of lameness in lambs are caused by
Interdigital dermatitis can cause severe temporary lameness
which interferes with grazing. Prompt treatment ensures that
there is no impact on growth rate but delayed treatment can cause
failure to gain weight or even weight loss
Interdigital dermatitis is the most common cause of lameness in
lambs and occurs most commonly when underfoot conditions are wet
often in late spring. At grass, the prevalence is much greater in
lambs than in ewes, but interdigital dermatitis can become
problematic in housed ewes, when straw bedding becomes wet and
warm. The interdigital skin is red and swollen and covered by a
thin layer of white exudate. There is no under-running of the hoof
wall or sole.
Fig 2 Scald; the interdigital skin is swollen and covered
by a thin layer of white exudate.
The diagnosis is confirmed by inspecting the sheep's feet after
removing any contamination.
Interdigital dermatitis causes severe lameness which is a major
welfare concern although sheep become sound 1-2 days after
Individual cases of interdigital dermatitis can be treated
topically using oxytetracycline aerosol sprays. When several
animals are affected, treating all sheep in the group in a 10% zinc
sulphate solution or 3% formalin in a footbath usually provides
effective control. After footbathing sheep must stand in a dry area
so that the formalin or zinc sulphate can dry on the feet - design
of the handling facilities is essential. It is usually necessary to
repeat the foot bathing at weekly or two weekly intervals
throughout the risk period to prevent disease transmission and more
lame sheep. No foot trimming is necessary for interdigital
Fig 3 These handling pens and footbath must be cleaned before
Prevention and control
Footbathing is most successful in treating interdigital
dermatitis in lambs and preventing footrot. There is no scientific
evidence that any one type of footbath treatment formulation is
more effective than another. At concentrations greater than
5%, formalin can cause severe irritation of the interdigital
skin. The practice of regularly replenishing footbaths with a
few splashes of concentrated formalin solution should be
Footrot is an extremely painful disease and affected animals can
lose weight rapidly. Sheep with footrot are very lame, remain
recumbent for long periods and may not bear weight on the affected
leg. When both forelimbs are affected, sheep walk on their
knees. There is swelling and moistening of the interdigital
skin with infection spreading to separate the horn tissue of the
sole from the corium and extend up the wall in neglected
cases. There is a characteristic foul-smelling discharge.
Footrot is caused by the bacterium Dichelobacter nodosus.
Fig 4 Footrot has caused severe lameness in all three Blueface
Leicester rams in this group.
Fig 5 Swollen knees caused by time spent grazing on his
The prevalence (percentage of affected sheep on any day) is
estimated to be 8-15 per cent in UK flocks. There is increasing
evidence that a high prevalence of lameness (>2%) is indicative
of failure to treat lame sheep appropriately (not quickly enough
and using the wrong treatment). One flock study reported an
annual loss of around £6 per lame sheep affected by footrot mainly
the result of lost production not treatment costs.
Inflammation and superficial infection of the interdigital skin
extends to under-run the sole and hoof horn of the inner hoof wall.
Further separation and under-running of the hoof horn of the sole
continues and may extend to the outer hoof wall. There is a
characteristic smell of necrotic horn/exudate. The whole hoof
capsule may be shed in severe cases. Chronic infection leads
to grossly mis-shapen and overgrown hooves.
Fig 6 Early case of footrot with infection spreading under the
horn tissue so that horn becomes separated from the sole.
This foot must not be trimmed.
Fig 7 Footrot where infection has spread under the horn tissue
of the sole. The reddened corium has become exposed causing
pain. This foot must not be trimmed.
Fig 8 Advanced case of footrot with infection
under-running the sole and extending up the inner hoof wall to the
coronary band. This hoof horn must not be trimmed.
In chronic cases, the hoof walls and toes become overgrown and
mis-shapen, trapping dirt and inflammatory exudate between the
inflamed, granulating soft tissues of the sole and overgrown
Fig 9 The hoof walls and toes have become grossly overgrown and
mis-shapen caused by prolonged lameness and ineffective
Fig 10 A neglected case of footrot with complete under-running
of the sole and an overgrown and mis-shapen outer hoof wall.
Excess flaps of horn can be trimmed about one week after antibiotic
treatment when the foot will be much less inflamed and
Fig 11 Neglected case of footrot - this must not happen.
Antibiotic treatment - injection and topical spray are essential.
Only large loose flaps of horn should be removed with sharp hoof
shears after an interval of about one week or so.
Fig 12 Hooves become overgrown because the sheep does not walk
on that leg. Grossly over-grown feet (see above) suggest and
extended interval to correct treatment.
Moderately to severely lame sheep must be examined that day.
Diagnosis of footrot is based upon the characteristic appearance of
lesions although it may prove difficult to differentiate from
contagious ovine digital dermatitis (CODD) in some cases and
veterinary examination is essential. Sampling for bacteriology is
rarely undertaken in the field because of cost.
Foot-bathing is not an appropriate treatment for sheep with
footrot although, if used correctly, it may limit the spread of the
disease during its early stages.
The best current treatment for footrot is an injection of long
acting oxytetracycline injected intramuscularly at a dose rate of
10 mg/kg, together with removal of any debris from the interdigital
space and use of an antibacterial spray. Most sheep recover
from lameness within a few days, a few may take up to 10 days and
lesions heal over a similar period. Affected sheep must be isolated
with other sheep undergoing similar treatment. Some veterinary
practitioners report a much better response using tilmicosin
compared to oxytetracycline when treating advanced lesions of
footrot however there are concerns about the routine use of
macrolide drugs in farm animals.
Paring the hoof horn in cases of footrot exposing the corium
delays healing and is not recommended. Overzealous paring and
exposure of the sensitive corium in combination with frequent
formalin footbath treatments may result in the generation of toe
Fig 13 Toe fibroma caused by excessive paring and exposure of
Fig 14 Toe fibromas can be very difficult to treat.
Foot paring may be undertaken when the sheep is no longer lame
and the foot is grossly overgrown. The grossly overgrown horn
should be trimmed with sharp foot shears after about one week when
the footrot lesion is much less inflamed. Only grossly
overgrown flaps of horn that could trap dirt should be removed. It
must be recognised that the foot has become overgrown because the
sheep has not been bearing weight on that foot.
Prevention and control
Foot trimming has no role in the treatment of footrot nor should
it be considered as a preventive method when planning control
programmes. Foot paring must not be undertaken when the corium is
exposed and bleeding. However, where the cause of lameness is
not obvious, and the corium is not exposed, careful paring of
overgrown horn may be necessary to check for the presence of white
line disease and an abscess.
Fig 15 Foot trimming has no role in the treatment of footrot
nor should it be considered as a preventive method. Excessive
trimming of the wall in this case causes most of the weight to be
carried by sole which is not normal.
Footbathing sheep before housing and after gathering, where
facilities are excellent and the standing is hard can kill off
bacteria on the surface of the foot and reduce transmission of
infection. Footbathing is most likely to be successful to
Trimming excess horn whilst leaving a weight bearing wall is
best done once the sheep is no longer lame; trimming should not be
viewed as part of the initial treatment for footrot. If a
chronically lame sheep does not respond to remedial treatment, it
should be culled.
All purchased stock must be quarantined for one month and
examined for footrot before introduction into the main flock.
Footbathing could be undertaken during this quarantine period as
directed by the farmer's veterinary surgeon.
Prior infection does not confer any appreciable immunity to
footrot. There are few reported flock trials of footrot
vaccines in the UK upon which to base informed opinion. It is
recommended that all sheep are vaccinated thereby limiting future
environmental contamination and challenge. A single dose of
vaccine is given which can be boosted four to six weeks later if
significant levels of disease still remain in the flock.
Subsequent doses should be administered according to prevailing
conditions or in anticipation of climatic conditions which favour
Potential disadvantages associated with vaccination include;
cost (£1.50 per dose), short duration (booster vaccinations
required every six months or before the anticipated challenge
period), and occasional severe localised reaction at the injection
Whole flock metaphylactic injection
Where the prevalence of lameness is very high, whole flock
metaphylactic injection has produced excellent results for the
control of footrot and CODD in carefully selected flocks with
secure perimeter fences and good biosecurity. Farmers should
consult their veterinary practitioner for advice on whole
group/flock antibiotic injection as this practice has been
questioned by the most recent RUMA guidelines.
RUMA guidelines are that "Fluoroquinolones, 3rd and 4th
generation cephalosporins and long acting macrolides have an
important place in the therapeutic armoury for serious diseases of
both animals and humans. The use of these classes in both human and
veterinary medicine has produced particular debate and the
following guidelines for use should be followed.
Fluoroquinolones, 3rd and 4th generation cephalosporins and long
acting macrolides should only be used therapeutically not for
Selecting sheep that are more resistant to footrot is desirable
and possible. Estimates from many countries indicate that
resistance to footrot in ewes is heritable at 10 - 20%. Currently
selecting replacements from ewes that have not had footrot,
especially in a group where there have been ewes with footrot will
help to reduce susceptibility to these conditions.