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
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.
- 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.
- 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
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.
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.