Understanding and Treating Mud Fever
The trouble with mud fever, also known as greasy heel, is that by the time you notice it, it’s usually already well-established. Immediate action is crucial to prevent it from progressing into a painful condition characterised by swelling, pain, lameness, scabs, discharge, and cracks in the skin. Multiple infections, including bacteria, fungi, yeasts, ringworm, and mites, can complicate treatment and prolong recovery.
Early Signs and Symptoms
The first signs of mud fever may include slight puffiness and reddening of the skin around the heel bulbs and back of the pastern. The area may appear wet and greasy as serum begins to ooze, eventually leading to a smelly discharge of pus. As the discharge dries, it forms thick crusts that protect the bacteria and fungi within the wounds. If left untreated, the condition can worsen, causing increased pain, heat, swelling of the lower limb, lameness, fatigue, and loss of appetite.
Risk Factors
Wet conditions irritate the skin, and horses with white legs, pink skin, thick coats, and feathered legs are particularly at risk, as the hair traps moisture and dirt against the skin. It is not the mud itself but the constant wetting and chilling of the skin that causes mud fever. Interestingly, mud fever is more common in horses whose legs are frequently washed and less common in those whose legs are rarely washed.
Causes and Infections
Mud fever is caused by the bug Dermatophilus Congolensis, which is a combination of a bacteria and a fungus. This bug can infect various animals, including sheep (causing lumpy wool and strawberry footrot), cattle, cats, dogs, goats, humans, pigs, and even crocodiles. It often lives harmlessly on the skin but can invade when the skin becomes soft and weakened. Secondary infections with bacteria like Staphylococcus, Streptococcus and Pseudomonas, yeasts, mites, and fungi can occur once Dermatophilus has taken hold. Leg mites, insect bites, and ringworms can also get involved, irritating the skin and causing itchiness. Diagnosing these infections may require deep dermal skin scrapings from the edges of lesions.
Treatment Strategies
There are many treatments for mud fever – and as with anything that has a whole lot of treatments, it is often because nothing is a guaranteed success. Treating mud fever can be challenging and may take weeks to fully heal, especially if the condition has become chronic.
There are three rules when using ointments:
Scab Removal: All scabs must be removed to allow ointments to penetrate effectively.
Drying the Area: The affected area must be completely dry before applying ointments to allow the ointment to penetrate
Generous Application: Apply ointments generously to the affected area.
Clipping the affected area (with clippers or good, curved scissors) and washing with an antiseptic solution can help remove scabs.
According to Doug English, a veterinarian with over 45 years of experience in equine practice, scabs protect the bugs and allow them to re-seed back into the skin. Recurrence is inevitable because Dermatophilus Congolensis thrives in moist conditions and will continue to grow and invade. Dr. English (http://turmericlife.com.au/) has developed a range of specialised formulas containing turmeric, whose benefits have been repeatedly confirmed, including by Dr. Michael Mosley on ABC Radio.
Scab Removal
Removing scabs without first softening them can be difficult and may cause discomfort for the horse. To soften the scabs, you can apply an Animalintex poultice for 24 hours, or use a generous amount of baby oil, aqueous cream, or udder cream. Cover the area loosely with plastic wrap (such as Gladwrap) and secure it with a bandage, starting at ground level and taping it to the hoof to prevent it from riding up to the pastern. After 24-48 hours, the scabs should be very soft.
Once the scabs are removed, gently rinse the skin and pat it dry with clean, absorbent tissue. Avoid rubbing with a towel, as this can be painful and further irritate the skin. You can use a hairdryer on the 'cool' setting to help dry the area. Initially, the legs may need to be washed daily to prevent the scabs from reforming quickly. However, be cautious not to wash the horse's legs too frequently, as this can strip the natural oils from the skin and potentially worsen the condition. Only continue washing as long as necessary.
Know when to get veterinary input
If you're having trouble removing the scabs, even after softening them for several days, or if you're struggling to keep the affected area clean, it's time to call your veterinarian. Your vet may need to take samples from the affected area to identify the specific bacteria or fungi involved. A correct diagnosis is crucial for determining the most effective treatment.
For example:
If the vet suspects an autoimmune disease, your horse may need corticosteroids.
If feather mites are suspected, you'll need treatment to eliminate the mites and prevent the trauma from itching.
If bacteria and fungi have penetrated deeper layers of the skin and even completely through the skin (cellulitis), a course of antibiotics may be required.
It's important to note that antibiotic creams are unlikely to kill all the bacteria, especially those deeper in the tissues. Oral or injectable antibiotics may be necessary for 4–6 weeks. However, antibiotics do not treat the fungal part of the infection, and there are real and increasing concerns about bacterial resistance.
Post-Infection Care
Once the infection has cleared, it is crucial to protect the new skin and hair. Remove the horse from wet and muddy conditions and apply liberal amounts of barrier creams and oils, such as pig oil, castor oil, goose grease, zinc cream, lanolin or petroleum jelly to protect the area while new skin and hair grow.
Hand-walking your horse several times a day can be very beneficial initially. Once any lameness has resolved, working on a dry surface that doesn't scratch the legs will help improve circulation and encourage healing. Roadwork is often the best option. Applying a barrier cream to dry and clean legs before exercise or turnout will help prevent the skin from coming into contact with bacteria. There are many preparations available, but those with a soothing emollient and oily base are the most effective.
Preventive Measures
Applying barrier creams to dry and clean legs before exercise or turnout can help prevent mud fever. If you decide to leave the mud on overnight and brush it off in the morning (which is more suitable for heavy-feathered or unclipped legs), the mud won't be trapped in the air and won't be in direct contact with the skin. In cold weather, this approach helps the legs retain more heat, reducing the chilling effect of cold water. Additionally, much of the mud will naturally fall off during the night, and grooming in the morning allows you to closely inspect the skin. However, be aware that the mud may conceal small wounds, and grooming can be time-consuming. Ultimately, you need to determine what works best for you and your horse.
Despite ongoing research, there is still no vaccine for mud fever. Effective control relies on understanding the contributing factors and knowing when to seek veterinary input. By taking proactive measures and providing proper care, you can help manage and prevent mud fever in your horse.
Dr Jennifer Stewart
BVSc BSc PhD Equine Veterinarian and Consultant Nutritionist
