A MUDDY BUSINESS – UNDERSTANDING AND MANAGING MUD FEVER
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Mud fever, also known as pastern dermatitis, equine dermatophilosis, cracked or greasy heels, is a common but potentially serious skin condition affecting horses, particularly in wet and muddy conditions. South Africa’s climate, with its seasonal rainfall and damp paddocks, can create the perfect environment for this condition to thrive. With the wet weather up in Jo’burg currently, now seemed as good a time as any to dive into the pathology, treatment and prevention of this tricky condition.
What is mud fever?
Mud fever is caused by a bacterial infection, primarily Dermatophilus congolensis, which thrives in damp and muddy conditions. The bacteria penetrate the skin through tiny cuts, abrasions, or prolonged wetness, leading to inflammation, scabbing, and sometimes secondary infections. While the infection commonly affects the lower limbs, particularly the pastern and fetlock areas, it can also occur on other parts of the body in severe cases.
Thankfully, though, mud fever is non-contagious, meaning it can’t spread from one horse to another or to humans.
How it arises
In wet and muddy conditions, horses’ skin is commonly softer. Mud rubs against this softened skin, damaging the surface and allowing bacteria to access it.
Horses with thick feathers are susceptible to the condition throughout the year, as they are at greater risk of leg mites. This leads them to stamp their legs because they are very itchy. Excessive itching may break the skin and the area becomes susceptible to bacteria. If you suspect your horse might have leg mites, speak to your vet for further advice.
Risk factors
There are several factors that make some horses more predisposed to mud fever than others. These include:
- Standing in muddy or wet conditions for extended periods
- Standing in dirty bedding
- Regular hosing of the legs, especially if they are not dried properly afterwards
- Having broken or damaged skin due to a wound such as an overreach injury
- Having white legs, as the pink skin found under the white markings is often more sensitive than the dark skin
- Having thin skin, such as is found in Thoroughbreds or Arabians, which tends to get damaged more easily
- Having a weakened immune system, which is usually secondary to another condition such as Cushing’s Disease. Horses with a lowered immune system are less able to prevent and fight off infections, so are more prone to many health conditions, including mud fever. If these horses suffer from mud fever, it can be more challenging to treat.
Did you know?
Mud fever can also occur on other areas of the body, such as the belly or the back and is commonly known in these cases as rain scald.
Recognising the symptoms
Mud fever commonly begins on the pastern or the heel and manifests through a range of symptoms, including:
- Crusty scabs and lesions on the skin
- Broken and/or damaged skin
- Matted hair or patches of hair loss with raw skin underneath
- A creamy, white, yellow or green discharge between the skin and the scabs
- Heat, pain, redness and swelling in the lower limb
- Sensitivity and pain, causing lameness in severe cases
Infections can develop underneath the scabs and you may see swelling of the leg in severe cases.
Did you know?
As mud fever can be painful, many affected horses will not tolerate the area being touched.
Treatment options
It is important to call your vet as soon as you suspect mud fever so that they can give you an accurate diagnosis and make sure treatment is tailored to meet your horse’s needs. Once your vet has made a diagnosis and recommended a treatment plan, they will usually be happy for you to manage the condition yourself. However, if your horse fails to respond to treatment or the mud fever worsens, you must contact your vet for further support.
A general treatment plan for mud fever includes:
- Cleaning and drying the affected area – Gently wash the area twice daily with an antiseptic solution such as chlorhexidine, then pat dry thoroughly with a clean towel. Avoid excessive scrubbing, as it can further damage the skin.
- Remove crusts carefully – If the scabs are loose, soak them with warm water or an antiseptic solution before gently removing them. Removing crusts allows air to reach the underlying tissues and aids in healing. However, if you do choose to do this you must be careful as it can be very uncomfortable for your horse and sedation may be necessary. Do not force scabs off unless expressly advised by your vet to do so, as this can be painful and worsen the infection.
- Keep the area dry – If possible, keep the horse in a dry, clean environment to prevent further contamination.
- Use bandages when necessary – In severe cases, bandaging the affected area can provide protection, keep it clean and reduce swelling. However, any bandages applied should be changed regularly to avoid trapping moisture.
- Creams – Severe mud fever may require repeat treatments and cream applied to the skin.
- Antibiotics – If the mud fever isn’t clearing up, your vet may take swabs to check for bacterial growth and sensitivity. This helps your vet to decide if antibiotics are necessary.
- Anti-inflammatories – Your vet may recommend these depending on the clinical signs and overall health of your horse.
If left untreated, mud fever can result in further complications, such as cellulitis and lymphangitis. These conditions are both bacterial infections of the lower leg that affect the blood and lymphatic vessels, often causing swelling, discomfort, and potentially long-term damage. If you notice any swelling, speak to your vet immediately.
Note: If mites or a fungal infection have triggered the mud fever, individual treatment for these causes may be needed.
Preventing mud fever
There are many ways to reduce the risk of your horse developing mud fever and they are all aimed at addressing the underlying causes. Here are some key steps to reduce the risk of mud fever:
- Manage paddock conditions – Avoid leaving your horse standing in wet and muddy conditions for long periods. Try to improve drainage or provide plenty of dry standing areas.
- Avoid washing—Avoid washing your horse’s legs when they are muddy. Rather wait until the mud is dry, then brush it off using a soft-bristled brush. If you do have to wash the legs, make sure you dry them thoroughly afterwards using a clean towel.
- Regular grooming – Check and clean your horse’s legs daily, removing mud and moisture to prevent bacterial build-up. A regular grooming practice also allows for early detection, which should make the condition easier to manage.
- Barrier creams—Waterproof barrier creams (such as zinc-based ones) can be used before turnout to create a protective layer between the skin and the mud. However, ensure the skin is dry and clean before application; otherwise, the cream can create the perfect environment for bacteria to grow.
- Protective boots – Boots designed for turnout can help prevent mud getting onto your horse’s legs, but they must be well-fitting to avoid rubs and sores, which can create bigger problems. These boots must also be removed as soon as your horse is in a dry area to allow the legs to dry thoroughly.
- Underlying conditions – Promptly treat any underlying conditions such as mites, fungal infections or wounds to reduce the risk of mud fever developing.
- Clip excess hair – Trimming long feathers around the pasterns can prevent mud from sticking and reduce moisture retention.
- Boost the immune system – A well-balanced diet with sufficient vitamins and minerals can support skin health and overall immunity.
Top tip
If your horse has thick feathers, you may need to carefully clip the hair from the lower leg to expose the skin to the air and make it easier for you to clean and treat.
Conclusion
Mud fever can be frustrating and painful for horses, but it can be effectively managed with proper care, treatment, and preventive measures. We all need to stay vigilant, particularly during the rainy seasons, to ensure that our horses are kept in clean and dry environments to minimise the risk of infection. By staying proactive, we can help keep our horses’ legs healthy and free from the discomfort of mud fever.