FOOT ROT
Foot rot, or infectious pododermatitis, is a hoof infection
commonly found in sheep, goats, and cattle. As the name suggests, it rots away
the foot of the animal, more specifically the area between the two toes of the
affected animal. It is extremely painful and contagious. most often it occurs
during
persistent periods of rainy weather along with temperatures
above 50°F
CAUSES
The cause of the infection are confirmed
as species of anaerobic bacteria, Fusobacterium
necrophorum and Bacteroides melaninogenicus. Both bacteria are
common to the environment in which predisposed animals live, and and Dichelobacter
nodusus that resides in the feet of infected animals.
The disease is usually
spread from infected carrier animals into the soil and then to the non-infected
feet of healthy animals.
Overgrown hooves will predispose an animal to foot rot. Wet soils, muddy
pens and filth increase the
possibility of disease outbreaks.
SYMPTOMS
1.
Inflammation of the hooves cause the animal not
to walk properly as a result of the pain caused by responsible bacteria (Fusobacterium necrophorum and Dichelobacter nodusus) - The sole and
the sidewall of the diseased foot appear ragged and rotten and have an
extremely bad necrotic odor.
2.
Reduce growth- The growth of an animal is
reduced because of the pain caused by the bacterial infection preventing the
animal from competing properly for both food and water for growth and survival
TREATMENT
The
control of ovine foot rot is based on several management practices that
decrease predisposing factors, and on the treatment and immunization of
infected and susceptible sheep. The best results are obtained when several of
the following methods are combined.
- Foot trimming: This reduces the number of cracks and crevices
where bacteria can hide, removes infected hoof, and exposes the organism
to air and various medications. All affected tissue should be trimmed away. Many times,
this involves removing a large portion of the hoof wall as well as the
overgrown portion. This is necessary if the medication and oxygen are to
reach the bacteria and kill them. Foot trimming should be done at least
one to two times per year as a part of normal management practices, and
more often in conjunction with footbaths in the control of foot rot. When
trimming feet, it is important to disinfect the trimming instruments (foot
shear, hoof parer, or knife) between animals to prevent spreading of the
infection. During a severe outbreak, trimming without any other treatment
may actually increase the severity of the disease. If there are problems
or questions on how much to trim, request the help of a veterinarian.
- Footbaths/Footsoaks: There are two different types of solutions
commonly used in foot baths: zinc sulfate and copper sulfate. For
treatment, they should be used 1-2 times per week for several weeks. They
may also be used routinely after foot trimming and as a preventative.
- Zinc sulfate solutions are
mild and effective and are the solutions of choice: 1 part zinc sulfate
to 9 parts water, or 10% weight (zinc sulfate) to 90% volume (water)
ratio.
- Copper sulfate solutions in
the proportions described above for zinc sulfate solutions are also effective
but will stain the hair or fleece blue-green and can be potentially toxic
if ingested.
NOTE: COPPER SULFATE SOLUTIONS SHOULD NOT BE USED
IN SHEEP.
- Dry chemicals: Zinc sulfate (dry) can be placed in a box in an
area sheep must walk through. This will not treat infected animals, but
will help decrease the spread of the disease. Lime, disinfectants, or
drying agents may be used around feed or water troughs to reduce moisture
and decrease the spread of the disease.
- Oral therapy: Zinc sulfate at the rate of 1/2 (0.5) gram per
day for 21 days may be helpful both in treatment and prevention,
especially if the diet is zinc-deficient. High levels of certain
antibiotics may also be helpful in some situations but should only be used
after consultation with a veterinarian.
- Injection of antibiotics: Penicillin and streptomycin combinations used
either as a one-shot treatment (1 ml/8 pounds) or every day up to ten days
has been proven to be effective in treating foot rot. Procaine Penicillin
G or long-acting penicillin products at the same dosage may also be
effective. Single injections of long-acting tetracycline have also been
successful in some cases. Use of any of these should be after consultation
with or by a veterinarian and should never be used on animals that are intended
for slaughter before an adequate withdrawal time.
- Topical medications: There are several different medications that can
be applied to the hoof immediately after paring that are helpful in
controlling foot rot.
- Zinc sulfate (10%) - 1/4
(0.25) pound in one quart of water.
- Copper sulfate (10%) in
vinegar - 1/4 (0.25) pound in one quart vinegar.
- Copper sulfate in pine tar - 2
parts CuS04 in one part pine tar.
- Oxytetracycline solution in
alcohol - one 25.69-gram pkg to 1/2 cup water, then add alcohol to bring
solution to 2 quarts.
- Penicillin in alcohol - 5
million units of potassium penicillin G with 10 cc (ml) water, then add
to 1 quart alcohol.
- Vaccination: Vaccines for Bacteroides nodosus are approved for use in the U.S. They may range in effectiveness from 0-100 percent; most users report from 60-80 percent success. The vaccine works not only as a preventative but has been shown to be fairly effective as a treatment. A regimen of two vaccinations given subcutaneously on the neck just behind the ear 4-6 weeks apart is used. Vaccination before the start of the wet season is recommended, followed by a booster each year prior to the wet season if eradication efforts have not been successful. Abscesses are common at the injection site but should not be treated. These will usually break and drain on their own with no ill effects to the sheep. For this reason, vaccination of show animals or animals that may be going to slaughter soon may not be practical. As always, follow label directions carefully. In the eradication protocol, vaccination can be done six weeks prior to the start of the program and the booster can be given when processing is started. This can increase the immunity, and some healing may be taking place by the start of trimming. Some labor savings can be made by doing the first vaccination at the start of the eradication program. Also, there will be savings on vaccine because the clean group will not have to be vaccinated a second time.
PREVENTION
It is always easier and less
expensive to prevent foot rot than to treat it after it has become established.
To remain disease free, there are five management principles that will help
keep foot rot from being introduced into a clean flock.
- Never buy animal (Cattle, Sheep and Goat) with foot
rot or from a flock infected with foot rot, even if the animal(s) appear
unaffected.
- Avoid buying sheep at sale yards or livestock markets
where clean and infected animal may have been commingled or run through
the same area.
- Avoid using facilities (trails, corrals, dipping
areas) where infected sheep may have been in the last two weeks.
- Never transport animal in a vehicle that has not been
properly cleaned and disinfected.
- Trim and treat the feet of all new arrivals, then
re-examine them periodically during the 30-day isolation period.
NOTE: The best method of foot rot prevention is to remove animals
from muddy, dirty and wet areas
for about 4 weeks so the
organisms present in the soil will die out or decrease in number.
PRACTICAL TREATMENT FOR FOOT ROT PROCEDURES
Remove the dead, rotten foot
tissue with shears or a sharp knife. Trim down until the healthy tissue is
found. Some bleeding will occur. This is necessary to remove the diseased
tissue.
After trimming their feet, the
animals should be forced to walk through a zinc sulfate foot bath
solution. Repeating the footbath
treatment 2 to 4 times at weekly intervals may be necessary. Let
animals stand in the foot bath
solution for approximately 30 minutes, followed by another period in a
dry lot to allow the solution to
dry on hooves. Do not place the foot bath where goats are likely to
drink from it.
The use of injectable antibiotics
is highly effective and penicillin, erythromycin or oxytetracycline can
be given under the advice of a
veterinarian.
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