Foot rot (aka hoof rot) has probably been around almost as long as sheep have had feet. It’s caused by two bacteria working in concert: Fusobacterium necrophorum (found wherever there is manure) and Dichelobacter nodosus. The latter organism can only live up to three weeks in the environment, but it can be perpetuated indefinitely on and in the hooves of sheep, goats, deer, horses and cattle. Clinical and subclinical (i.e., no visual symptoms) carriers are the most common way D. nodosus enters a flock; other routes include contaminated hoof trimmers, equipment, human hands, tires, footwear, contaminated pastures and facilities.
When both organisms are present on a sheep’s hoof, they work together to dissolve the connection between the hoof and foot. Different strains of D. nodosus vary in the strength of the protein-dissolving enzymes they produce. Early in the disease’s progress, there is inflammation, moistness, pain and a fetid smell between the toes. As the condition advances, the animal becomes increasingly lame and experiences severe pain. These bacteria thrive when they gain access to deeper anaerobic parts of the hoof wall. Even mildly affected animals may limp and lose weight, especially if they must graze.
What Puts Our Sheep At Risk?
Predisposing factors for foot rot are environmental, genetic, nutritional and managerial. The environment must be moist and contain both organisms, and rough footing—such as hard plant stubble or jagged gravel—can damage hooves and make it easier for the pathogens to gain a foothold.
Genetic susceptibility to foot rot and resistance factors are being investigated. Scientists have found that some sheep are actually resistant to foot rot. Diets with sufficient protein and zinc support hoof health. Management issues, such as sanitation and frequency of hoof trimming, are also factors.
Treating Foot Rot
Foot-rot treatment has evolved over time. Some new protocols call for not trimming hooves on affected animals and using systemic antibiotics and/or 10- to 20-percent zinc sulfate footbaths instead. A quick run through a communal footbath is not effective, though. Each hoof needs 10 to 60 minutes of soaking, with 30 minutes of drying time on clean straw or concrete afterward. Ask your veterinarian about which injectable antibiotic to use.
Preventing Foot Rot
To reduce the risk of foot rot, fence sheep away from wet and muddy areas. Work with your conservation district or county extension agent to implement best management practices for mud control, especially around feeders, waterers and housing.
Other prevention actions include regular examination of all hooves and trimming them when necessary. You could choose to use a foot rot vaccine, and in chronic cases, it may be necessary to identify and cull suspected carriers.
However, take solace in the fact that foot rot can be readily eliminated from a farm through diligent effort:
- Examine every foot on the farm. All feet should be trimmed to prevent cracking and/or rolling under of hoof wall. Any tracks or pockets of infection should be
exposed and eliminated. - Trim hooves on a tarp. Pick up hoof trimmings and remove from sheep contact area.
- Separate healthy animals from infected animals. Infected animals could be culled immediately or culled if they don’t respond to treatment.
- Clean and disinfect all equipment before and after use. This is especially true of hoof trimmers between animals.
- Provide a balanced diet, especially with regard to protein.
- Keep a closed herd, and don’t take sheep off the premise. If this can’t be avoided, use a quarantine pen for animals coming onto the farm. Trim all incoming hooves, soak them in a foot bath of zinc sulphate or copper sulphate for 10 minutes at least once a week, and keep them in a dry area for a month. Observe closely for any signs of hoof rot.
- Leave areas where infected animals grazed vacant for at least one month.
- Monitor all sheep daily. Look for signs of lameness, foot swelling or redness between toes.
This article was vetted by Dr. Lyle G. McNeal, a livestock specialist in the Department of Animal, Dairy and Veterinary Sciences at Utah State University.
This article originally ran in the July/August 2016 issue of Hobby Farms.
