SHEEP FOOT CARE AND DISEASES
In order for sheep to efficiently convert
forages to meat and wool, the condition of their feet must not become a
limiting factor. The growth of sheep's feet in temperate climates requires
trimming and related care every four to six months.
Foot growth is affected by breed of
sheep, soil moisture and soil characteristics. Sheep grazed on rocky, dry
soil may not require the extent of foot care needed for sheep on soil that
is free of rocks and higher in moisture content.
An illustration of an untrimmed and
a properly trimmed foot is shown in Figure 1. The foot should always be
trimmed from the heel to the toe to remove excess growth of the "horny"
portion of the hoof (Figure 2).
Figure 1. An untrimmed (l) and a properly
trimmed (r) foot
Some points to consider in the trimming
1.Combine foot care with other operations,
such as worming, shearing, etc. Many producers trim feet before flushing
and combine the operation with worming and vaccinations. Also check the
feet at lambing when the ewe is closely confined.
2.Avoid periods of stress such as late
pregnancy or extremely hot weather.
3.The feet of sheep coming in from
pastures with heavy dew or rain on them will be softer and easier to trim.
4.Sheep which show abnormal foot growth
should be identified for closer observation and/or culling.
Figure 2. Always trim the foot from the
heel to the toe.
Diseases of the Sheep's Feet
Several diseases result in limping
or reduced mobility in sheep. The producer should become familiar with
the characteristics which distinguish each of these so they may be properly
This disease is characterized by swelling
of the soft tissues immediately above the hoof and, in advanced cases,
draining abscesses in this area and between the toes. Foot abscess is caused
by bacterial infection of damaged foot tissue. Any conditions, such as
grazing stubble, etc. which increase foot irritation result in a higher
incidence of the disease.
The front feet are most commonly affected.
Infection may be limited to one foot or to one half of the foot.
Affected sheep should be isolated,
their feet inspected and trimmed and the infection cleaned and treated
with anti-bacterial compounds. Once the infection site is clean, it will
normally begin to heal.
Foot scald is characterized by a softening
of the area between the toes and is usually associated with wet pastures
or damp bedding. It is a form of superficial dermatitis associated with
the conditions and microorganisms which may also result in foot rot. Sheep
will become slightly to moderately lame depending on the stage of infection.
The forefeet are more often affected than the rear feet.
Treatment should consist of moving
the sheep to a dry area, trimming the feet carefully and using a topical
treatment on the feet of 10% zinc sulfate in water (1/4 pound in 1 quart
Failure to treat foot scald may lead
to foot rot when conditions favor such development (see "Contagious Foot
The lameness related to laminitis is
caused by inadequate blood flow in the foot. This effect of founder (or
grain overload) is normally associated with digestive problems resulting
from excessive intake of grain, which usually masks the effect on the feet.
Such animals usually die before the feet become involved. Recovered animals
may exhibit unusual foot growth and/or permanent lameness.
Feeding management is the key to prevention
of founder and laminitis.
The lameness caused by contagious ecthyma
is the result of vesicles (blisters) appearing on the skin near the top
of the hoof wall. Simultaneous vesicles appear on the mouth and other areas
on the sheep's body. The resulting lesions can be treated by applying an
ointment containing a broad-spectrum antibiotic to the affected area.
The disease can be prevented by vaccination.
Since humans can contract sore mouth (orf), care should be taken to prevent
infection when treating infected sheep.
Other considerations when limping or
lame sheep are observed are physical injury, foreign material between the
toes, arthritis or other joint problems, corns on the feet and acute mastitis.
Contagious Foot Rot in Sheep
Contagious foot rot is an age-old malady
of sheep and currently a major production problem in many areas of the
United States. Foot rot is generally more prevalent in temperate climates.
However, the disease has become widespread and of more recent concern to
western producers, especially in the intermountain area.
Foot rot is one of the most economically
devastating diseases of sheep. The disease is considerably easier to prevent
than to control or eradicate.
Eliminating the disease in affected
flocks requires a strong commitment to strict treatment practices. Dedication
required for such an effort ultimately determines the success of foot rot
Cause and Disease Process
Foot rot is caused by an interaction
involving two types of bacteria that grow in the absence of oxygen. Bacteroides
nodosus, bacteria that can live only in the animal's foot, can be eradicated
from the flock. If B. nodosus is not present, foot rot will not
occur. Fusobacterium necrophorum, which helps B. nodosus
penetrate the skin and tissues, is a normal inhabitant of soil and sheep
manure and is always present where sheep are raised.
In the usual course of infection, skin
between the toes becomes wet, macerated and infected by F. necrophorum.
Then, B. nodosus is able to become established in the deeper layers
of the skin where it produces an enzyme that liquefies tissue protein around
it. By this means, the infection separates the heel, sole and wall of the
hoof from their attachments to the foot, causing inflammation, lameness
and odor. Other bacteria may also be present and contribute to the inflammation.
Lameness is usually the most obvious
symptom of contagious foot rot, although not all sheep with early infection
become lame. One or more feet may be affected at the same time. The first
visible lesion is a moist, reddened area between the toes. Subsequently,
the infection spreads under the sole and wall of the hoof and a characteristic
foul odor is present.
Not all lame sheep have foot rot; therefore,
feet should be closely examined before reaching conclusions. When the cause
of the lameness is uncertain, consult with your veterinarian.
The primary organism causing foot rot
is spread from infected sheep to moist soil and back to noninfected sheep.
The disease is most commonly introduced into a clean flock by the purchase
of infected sheep. Other modes of transmission include mixing with an infected
flock, letting infected strays enter the flock or the use of corrals, watering
areas, trails or trucks within a few days following an infected flock.
Ideal environmental conditions for
transmission occur when the soil temperature is 40° to 70° F and
soil or bedding stays wet. Any factor which causes injuries to the feet
will increase the likelihood of infection.
The B. nodosus organism does
not survive longer than two weeks in the soil. However, it may remain in
the hooves of carrier sheep for extended periods of time.
Some infected sheep may seem to recover,
but unless they have been properly treated and the infection eliminated,
foot rot will appear during the next wet season.
Producers who do not have contagious
foot rot in their flocks should be aware that it is much easier and less
expensive to prevent than to deal with the disease after it becomes established
in the flock. Thus, producers must make every effort to maintain the foot
rot disease-free status of their sheep.
Several management practices minimize
chances of introducing contagious foot rot into a clean flock:
1.Never buy sheep infected with
foot rot. Avoid buying apparently clean sheep from infected flocks.
Avoid buying sheep at sale yards where clean and infected sheep are penned
2.Avoid common-use trails and corrals
where infected sheep have traveled or have been penned during the preceding
3.Insist on proper cleaning and
disinfection of commercial vehicles before transporting sheep.
4.Assume all new additions to your
flock are infected with foot rot. Always isolate new animals for at
least two weeks, trim all feet immediately upon arrival, treat feet of
new sheep following trimming and re-examine periodically during the quarantine
period (see "Treatment of Infected Sheep").
Effort may be directed toward temporary
control of the disease or toward complete eradication. Under certain circumstances
and/or during certain times of the year, temporary control may be the only
realistic solution. However, eradication is possible and eventually should
be the goal of every producer.
Treatment of Infected Sheep
1.Vaccination: Use of vaccines
can significantly decrease the spread of foot rot in flocks where the causative
organism(s) are of the same serotypes as those contained in the vaccine.
Vaccines also may be helpful as a treatment.
The usual dosage schedule calls for two doses given subcutaneously behind
the ear four to six weeks apart. The last dose should be given two weeks
or so before a seasonal outbreak is anticipated, since the immune stimulation
is of short duration. Vaccination can be useful during an outbreak. Vaccines
are most beneficial when used in conjunction with other foot rot control
measures such as hoof trimming and foot bathing.
Foot rot vaccines currently used are
manufactured in Australia and New Zealand and contain eight serotypes of
nodosus isolated in those two countries. These vaccines may not always
be as effective in the U.S. where more than 20 serotypes of B. nodosus
are known to occur. When field tested in U.S. flocks, their effectiveness
has been reported to range from 0% to 100%. However, in most large vaccination
trials, flocks infected with the same or similar
B. nodosus serotypes
as those contained in the vaccine had efficacy values ranging from 60%
Tissue reactions at the sites of injection
have been common. Some sheep have developed large lumps which have abscessed
and drained before healing. This adverse reaction makes the use of present
products questionable in market lambs and purebred show sheep. As with
all biologics, the manufacturer's instructions for storage and use should
be carefully followed.
2.Foot bathing: Use of walk-through
foot baths of 10% zinc sulfate or 10% copper sulfate every fifth to seventh
day will greatly reduce the spread of foot rot to normal animals. Enforced
daily self-foot bathing with 10% zinc sulfate also reduces spread and will
help most infected animals recover.
The foot bath can be situated between
food and water. These methods will not "cure" carriers or those with severe
undermining of the hoof unless their feet are carefully trimmed (see section
Plans for foot baths are available
from your local Cooperative Extension Service office.
3.Foot soaks: 10% zinc sulfate
can be used for prolonged soaking of feet for a more effective treatment.
Addition of a wetting agent or detergent containing sodium laurel sulfate
will aid in the penetration of the chemical into the hoof.
Trimming the infected feet is recommended,
but a significant number of untrimmed infected hooves will respond.
Formalin must not be used for soaks
as it will severely burn the feet (see section on "Medications").
4.Dry chemicals: 10% zinc sulfate
in lime can be placed in a box between feed and water to reduce spread
of foot rot. This is particularly useful during freezing weather when a
solution would freeze.
This method is not effective for treatment
of diseased animals (see "7. Topical medications").
5.Trimming: Many medications
are effective when properly used, but to maximize their effect, the foot
must be thoroughly trimmed to expose all infected tissue. No treatment
will work if the medication can't reach the infection. All diseased, dead
and undermined hoof areas must be pared away to allow medication and air
to reach causative organisms. Topical medications should be sprayed on
immediately after trimming, and animals should then be foot bathed.
Foot trimmers should be cleaned thoroughly
and dipped in disinfectant after trimming an infected hoof.
6.Dry pens: Feet must have prolonged
exposure to moisture for foot rot to develop. The drier and less confined
the sheep, the slower the spread of foot rot. If infected sheep can be
placed in a dry area (which has been free of sheep for two weeks) after
treatment, the treatment will be considerably more effective.
7.Topical medications: These
are medications sprayed or painted on the feet just after trimming or when
foot bath facilities are unavailable. Trimming is essential for topical
medications to be effective. Ten percent zinc sulfate in water, 10%
copper sulfate in vinegar or two parts copper sulfate in one part pine
tar and 10% formalin in water have been shown to be the most effective
topical treatments. Antibiotics in alcohol solution have also been reported
to be from 50-90% effective under these conditions:
• feet were thoroughly trimmed,
• medication was applied once, and
• sheep were held in a dry area.
All of the above medications (except
pine tar) can be applied with an aerosol hand sprayer, and 5 to 10 ml will
be needed per infected foot. (For mixing directions, see section on "Medications.")
8.Antibiotics: The use of systemic
antibiotics or antibiotics in the foot is expensive and of limited success.
After treatment, the sheep should be held in a dry area for at least 24
hours to give the medication time to work.
The best control of this disease can
be obtained through the use of combinations of treatments. Vaccination,
foot soaking of the entire flock at five- to seven-day intervals and separation
of limping animals for trimming and hour-long foot soaks, for example,
would be an excellent combination.
Another recommended control method
using a combination of treatments would be enforced self-footbathing and
separation of infected sheep which do not respond within 14 days. Those
separated could be treated by trimming and soaks.
First Week: Carefully and thoroughly
trim all feet on all sheep. Separate any sheep which show evidence of having
or having had foot rot. Distorted, extremely hard hooves, small dry pockets,
loose or separated hoof wall and/or a strong, sweetish, sickening odor
are all indications of foot rot. If bleeding occurs early in the trimming,
examination of the tissues is particularly difficult. Turn the animal loose
and retrim later after the bleeding has stopped.
Foot bathe sheep which show no evidence
of foot rot, and place them in a dry area that has been free from sheep
for at least a week. Permanently identify affected sheep; then, foot soak
using zinc sulfate with detergent for one hour and keep them isolated from
all other sheep.
Second Week: Treat affected
sheep for the second time. Observe the unaffected sheep closely for signs
of lameness. Any lame sheep should be examined immediately. If the cause
is determined to be foot rot, all sheep in that group should again be trimmed
and examined as before.
Fourth Week: Carefully trim
and examine the affected group. Those that are lacking any signs of foot
rot at this point can be returned to the clean group. Those that have remained
infected should be culled at this point. If this is not practical, further
trimming and foot soaking can be employed.
If the numbers are few, individual
sheep can be treated very effectively following these steps:
•Fill a bootie made from a plastic
bag with zinc sulfate and detergent-soaked cotton or wool.
•Tape the bag onto the foot under the
•Leave it on no longer than two days.
As long as the sheep area remains dry,
any remaining foot rot will remain quiescent. Be especially observant after
sheep are exposed to moisture (irrigation, rain or snow).
This is an excellent time to retrim
and examine feet of all sheep. If this job is put off and limping sheep
are suddenly observed, remember the first sheep to show signs are the carriers.
They should be removed immediately. Don't wait any longer to examine the
rest of the flock. Isolate the affected animals, foot bathe clean sheep
and return them to a clean area.
Vaccination and/or antibiotics can
be used in conjunction with this schedule at any point. If the weather
or pens are not dry when this effort is started, vaccination of all the
animals at the beginning and three to four weeks later is recommended as
it will help reduce spread.
If the weather or pens are not dry
during this control effort, the clean group should be examined and trimmed
every 10 to 14 days until no new cases are found for three examinations.
After completing the treatment schedule,
watch the flock closely for several months to ensure that some cases of
foot rot were not overlooked.
• Trim • Treat • Isolate • Cull.
Eradication uses the same methods outlined
above, but requires more commitment, perseverance and willingness to cull.
An initial increased expense in labor and facilities will be required,
but will pay off many times over in the long run.
Even dedicated use of the above control
methods will not eliminate all carriers from a flock. Therefore, to eradicate
foot rot, it is essential to have facilities for keeping infected animals
isolated and to cull animals with recurring foot rot infection.
Foot Baths: Zinc sulfate is
available in the following forms:
Zinc sulfate (monohydrate) (Zn
SO4 *H2O) containing 35.5% zinc. Zinc sulphate (heptahydrate)
(Zn SO4 + 7H2O) contains 22.7% zinc. A 10% solution
= 8 pounds in 10 gallons of water. (Hot water will hasten dissolving.)
Copper sulfate (CuSO4, Bluestone,
Blevitriol) (10% solution = 16 pounds in 20 gallons of water). Hot water
will hasten dissolving. Addition of some vinegar will aid dissolving in
hard water. It should not be put in metal containers as it is quite corrosive.
Copper and zinc are very toxic if ingested by sheep. Store any unused solution
in an area inaccessible to animals.
Foot Soaks: Zinc sulfate 10%
(mixed as above) plus a wetting agent high in sodium laurel sulfate 0.2%
vol./vol. (2/3 cup per 20 gallons).
Dry Baths: Zinc sulfate 10%
in lime = 10 lbs agricultural grade zinc sulfate in 90 lbs lime. Mix well.
1. Zinc sulfate, 10% in water Ú
1/4 lb in 1 quart of water.
2. Copper sulfate, 10% in vinegar Ú
1/4 lb in 1 quart of vinegar.
3. Copper sulfate in pine tar Ú
2 parts of copper sulfate in 1 part pine tar.
4. Oxytetracycline solution in alcohol
Ú add 25.69 grams (one packet) of Terramycin soluble powder to 1/2
cup of water; add alcohol to bring solution to 2 quarts.
5. Penicillin solution in alcohol Ú
(10,000 units/ml) mix 5 million units of potassium penicillin G with 10
cc water and add the solution to a pint of alcohol.
The author acknowledges the use of material
in this publication from the Sheep Production Handbook 1988 SID-ASIA
6911, South Yosemite Street, Englewood, Colorado 80112-1414 and related
Where trade names are used, no endorsement is intended, nor criticism
implied of similar products not named.