Managing Mud Fever in Horses: Effective Strategies for Prevention and Treatment

Addressing mud fever in horses requires tackling a bacterial skin condition that can worsen if not promptly managed.

Our comprehensive article simplifies the intricacies of this disease, providing crucial insights into recognising the signs, implementing immediate treatment, and employing preventative measures to protect your horse’s health effectively and efficiently.

Understanding Mud Fever: Equine Pastern Dermatitis

Equine pastern dermatitis, commonly known as mud fever, mud rash, scratches, dew poisoning, or greasy heel, is a non-contagious skin condition characterised by irritation and crusting, often resulting from wet and muddy environments, that primarily affects horses.

It starts at the pastern, a part of the horse’s leg, but may spread up the lower leg. Mud fever commonly forms on the pastern and heels, which are the typical locations affected.

Horse’s pastern dermatitis often begins as a small lesion at the back of the pastern, on white legs, where the hair is very thin. This may be accompanied by flaking skin and redness if the horse has white hair and pink skin. It is important to regularly inspect and maintain the health of the horse’s lower legs, as these are the areas most affected by mud fever.

The thin covering of hair on the back of the pastern makes it vulnerable to irritation, skin breaks and sun damage. Factors such as coarse or sharp plant/grass edges, dust, or dirt can break the skin, providing an entry point for infection.

Prolonged wet weather and damp conditions can compromise the skin’s barrier function, increasing susceptibility to mud fever. Waterlogging from wet grass or muddy ground softens the skin, making it more prone to damage. Once the epidermis is breached, bacterial infection can occur, leading to pastern dermatitis, which is more frequently observed on white legs.

The condition is characterised by heavy, tightly adherent scabs over raw, red, and inflamed lesions. While fungal infections are often blamed, this is almost exclusively a bacterial infection.

Bacterial infection

A recent Swiss study looked at the skin bacteria living on the legs of horses with mud fever (equine pastern dermatitis) compared to healthy skin. Researchers found that the mix of bacteria was very different on diseased skin, and it also varied depending on the type of lesion.

In oozing sores, bacteria like Streptococcus and Corynebacterium were most common, while in the thicker, scabby forms, Staphylococcus was the dominant bug. This shows the cause is not one germ, but shifts in the normal skin bacteria when the skin barrier is weakened. The findings suggest that better treatments might come from targeting the specific bacteria linked to each type of lesion rather than using a one-size-fits-all approach.

Another culprit is the bacterium Dermatophilus congolensis. This is the same organism that causes the skin disease on the backs of horses and ponies called rain scald.

This bacterium thrives in anaerobic, wet and damaged skin conditions. If left untreated, it can result in serious complications, including cellulitis and lymphangitis. These conditions can cause significant swelling and discomfort in the horse’s lower leg. This requires immediate medical attention.

When initial treatments for prove ineffective, a veterinarian may conduct a swab test. This test checks for bacterial growth and sensitivity, helping to determine if antibiotic treatment is required.

Swabs should also be taken for an accurate diagnosis. Pemphigus Foliaceus can be misidentified as mud fever. A swab would be needed if the infection were long-term and not responding to treatment, just to check.

In persistent or severe cases, a blood test may be recommended to check for underlying diseases such as Cushing’s or other systemic issues that could affect recovery.

Fungal infections

Recent reviews and microbiome studies consistently show that mud fever is multifactorial, with bacteria (Staphylococcus, Streptococcus, Corynebacterium) and mites (Chorioptes) being the most consistently associated factors (Gerber et al., 2023).

However, a variety of fungal organisms, including those from the phylum Zygomycota and the genus Malassezia, have been associated with pastern dermatitis in horses.

Other causes

Another form of pastern inflammation is caused by a disorder of the body’s immune system, which attacks the skin. This is known as leucocytoclastic vasculitis and targets the unpigmented areas of the lower limbs. Leucocytoclastic vasculitis is one of several possible skin reactions that can occur due to immune system disorders, leading to various inflammatory responses in the skin.

The condition tends to spread upwards from the coronary band and is most commonly seen on white socks or pasterns exposed to sunlight. Leucocytoclastic vasculitis is believed to be triggered by UV light, often in combination with underlying sensitivities or immune dysfunction. Affected horses typically develop crusting, oozing lesions, swelling, and discomfort, and the condition can closely resemble mud fever in its early stages.

However, because it stems from an immune-mediated reaction rather than external infection, treatment often requires anti-inflammatory medications, sunlight avoidance, and long-term management of immune health, rather than standard antimicrobial approaches.

Risk Factors for Developing Mud Fever

There are several risk factors for developing this problem in horses. These include:

Wet and muddy environment: Constant exposure to muddy or wet conditions can soften the skin and make it more susceptible to infection. In this scenario, the skin softens and mud rubs against this softened skin, causing damage to the surface where bacteria can enter.

It’s not just winter weather though, as the wet of morning dew or rain on long grass in summer appears to create a softened skin, also causing the potential for damage.

Coarse or sharp plant/grass edges: These can break the skin, providing an entry point for infection. Coupled with wet, this can cause a mud fever patch.

Heavy soil: Heavy, clay-like soil can stick to the horse’s skin and create an environment that encourages bacterial growth.

Standing in mud: Keeping the horse standing in mud for extended periods can exacerbate the condition.

Excessive sweating under tack or rugs: Excessive sweating can create damp, irritated skin on the horse’s legs, making them prone to bacterial or fungal infections similar to rain scald. Monitoring and managing sweating levels is important as part of preventative care.

Dust/Dirt: These can become trapped in the skin creases, leading to skin breaks and subsequent infection. Regular grooming helps to keep the skin clean and healthy and is essential for maintaining the health of the horse’s legs to prevent mud fever. If a horse is not groomed regularly, dirt and bacteria can build up on the skin.

Over washing of legs: both with just water and water and detergent, can create mud fever due to waterlogged skin.

Sunburn: Can be the first step in the development of skin infections in horses. This is especially common in horses with pink, non-pigmented skin on their legs or faces, such as those with white socks or blazes, which are more vulnerable to UV damage.

Plants: Certain plants can cause photosensitivity in horses, making the skin, particularly non-pigmented areas like white socks, more vulnerable to sunburn and subsequent mud fever.

This condition occurs when horses ingest or come into contact with photosensitising compounds found in plants such as St John’s Wort, clover, and ragwort.

These compounds circulate in the bloodstream and react with sunlight, damaging the skin at a cellular level. The result is inflamed, peeling, or blistered skin that becomes cracked and sore, creating the perfect entry point for bacteria.

Poor quality hay: This has been identified as a risk factor for various horse diseases, although its direct link to mud fever is not clearly established, it is likely to be linked with poor mineral and protein levels.

Poor nutrition: A horse with a poor diet may have a weakened immune system, making it more susceptible to infections like mud fever. Ensuring a balanced diet with optimal levels of key minerals, sufficient protein levels and omega-3 fatty acids will help support the immune response.

Lack of sunlight and air: These conditions can promote the growth of anaerobic bacteria, which are often involved in mud fever.

Underlying health conditions: Horses with underlying health conditions, such as a compromised immune system, are more at risk.

Breed: Some breeds of horses are more prone to developing this issue than others.

Age: Older horses may be more susceptible to mud fever due to a weakened immune system.

Previous history: Horses that have had mud fever before are more likely to develop it again.

It is important to check your horse’s legs daily to detect early signs of mud fever or other leg issues. Daily inspections help in early diagnosis and prompt treatment, especially in muddy or wet conditions.

Federici et al. (2015) conducted a comprehensive clinical analysis of 974 three‑year‑old Franches‑Montagnes horses to explore whether coat characteristics, specifically white leg markings, impact skin and hoof health. The study revealed that horses with white leg markings had a 2.6‑fold higher prevalence of pastern dermatitis compared to those with fully pigmented skin (p <  0.0001).

Additionally, a higher White Marking Index (WAI) correlated with increased incidence of sunburn (p = 0.022). Interestingly, overall coat colour, such as chestnut or bay, showed no significant association with skin disease risk.

These findings highlight that unpigmented, white‑marked areas may be more vulnerable to environmental insults like mud and sunlight, suggesting a need for targeted preventive care.

Are mycotoxins a risk factor?

The primary role of mycotoxins in mud fever is their ability to compromise the horse’s liver health and immune response. Horses affected by mycotoxins may have impaired liver detoxification and increased systemic inflammation, making it harder for the body to fight off infections or to heal from them efficiently.

Additionally, certain mycotoxins can directly affect the skin and mucous membranes, leading to increased sensitivity, irritation, and slower wound healing.

Recent research has strengthened the link between forage mycotoxins and equine liver disease. Durham (2022) found several hepatotoxic mycotoxins—including fumonisin B1, aflatoxins, and zearalenone – exclusively in forage from liver disease outbreaks, with fumonisin B1 significantly elevated in affected horses’ forage (Durham, 2022).

A follow-up study confirmed that 96% of forage samples fed to horses with liver injury contained multiple mycotoxins, often at potentially harmful concentrations (Graham-Mackenzie, 2023).

Together, these findings suggest that forage-associated mycotoxicosis is an under-recognised cause of liver disease in horses, which can predispose them to photosensitization and secondary mud fever.

Preventing the effects of mycotoxins starts with reducing exposure. The most important step is to ensure that all forage and bedding is clean, dry, and free from mould. Hay and haylage should be stored properly, inspected regularly, and never fed if there is any sign of mould or musty odour.

Bedding such as straw or shavings should also be kept dry and changed frequently to avoid fungal growth, especially in damp weather.

While mycotoxin issues are more commonly associated with hay, haylage, and stored feed, pasture grasses can also harbour fungi that produce harmful mycotoxins, especially in wet, humid, or stressed conditions.

How Grass Can Develop Mycotoxins

1. Fungal Contamination on Living Grass
   Some fungi can infect grass while it is growing. These fungi may produce endophyte toxins or field mycotoxins, especially under stress conditions like drought, overgrazing, or nutrient deficiency.
2. Weather Conditions
   Prolonged periods of warm, wet weather can encourage fungal growth on pasture, particularly in late summer and autumn. These fungi can colonise the outer layers of the grass blades and produce toxins, especially in areas with poor drainage or heavy grazing pressure.
3. Decaying Plant Matter
   Horses grazing on paddocks with a lot of dead or decaying grass, trampled vegetation, or mouldy patches (often around feeding stations or overgrazed areas) may ingest or come into contact with fungal toxins.
4. Fungal Spores in Soil or Manure
   Certain fungi that produce mycotoxins can also be present in the soil or decomposing manure, especially if organic matter builds up and is not well managed.

Mycotoxins of Concern in Grass

• Slaframine: Produced by Rhizoctonia leguminicola, often found on clover in damp conditions. Known for causing excessive salivation (“slobbers”).
• Zearalenone, aflatoxins, or trichothecenes: While more commonly found in stored grains or hay, they can occasionally develop on pasture under the right conditions.
• Endophyte toxins: Found in certain grass species like tall fescue or perennial ryegrass, particularly in the USA, though less common in the UK and Europe.

Risk Factors to Watch For

• Poorly drained or compacted fields
• Overgrazed or stressed pasture
• Warm, wet, and humid weather
• Visible mould, dead patches, or rotting vegetation
• Horses showing unexplained symptoms (e.g. photosensitivity, poor coat condition, compromised immune response, or recurring skin issues)

How to Reduce the Risk From Mycotoxins

• Rotate grazing to prevent overgrazing and pasture stress.
• Rest and reseed damaged paddocks to improve grass health and reduce fungal pressure.
• Avoid grazing on very wet, trampled areas, especially near feeders or gates.
• Remove dead or mouldy plant material from fields when possible.
• Consider a mycotoxin binder in the feed if you suspect exposure, especially during high-risk seasons or in horses with recurrent skin or immune issues.

In summary, while grass is not the most common source of mycotoxins, it can be a risk for developing mud fever, particularly when pasture is stressed, wet, or poorly managed.

This risk is often overlooked, but it may contribute to systemic issues like photosensitivity, mud fever susceptibility, or immune suppression, particularly in sensitive horses. If recurrent skin or health issues are present despite good management, it’s worth considering pasture-borne mycotoxins as a contributing factor.

Feeding a mycotoxin binder is good insurance where mycotoxins are suspected, particularly on pasture. These are supplements designed to bind to mycotoxins in the gut and prevent them from being absorbed into the bloodstream. Common binders include bentonite clay, activated charcoal, and Mycosorb.

Supporting overall liver function and skin health is also key in reducing the impact of mycotoxins. This includes ensuring the horse receives a balanced diet with levels of zinc and copper high enough to balance iron and manganese levels.

Vitamin E is also important along with omega 3 in winter or where horses are not grazing green and growing spring or summer pasture. These nutrients support detoxification, immune response, and tissue repair.

While mycotoxins alone don’t cause mud fever, they can tip the balance in horses that are already vulnerable due to wet conditions, pink or damaged skin, or exposure to mud and bacteria.

Addressing mycotoxin exposure can be a valuable part of a broader mud fever prevention strategy, particularly in horses that experience repeated or unexplained flare-ups despite good skin care and turnout management.

Remember, prevention is always better than a cure. Regular grooming, keeping the horse’s environment clean and dry, spotting lesions early and ensuring the horse has a balanced diet can help to prevent mud fever.

Recognising the Signs of Mud Fever in Horses

Spotting signs at an early stage is vital for tackling the condition quickly. Mud fever most often affects the horse’s lower legs. It is characterised by distinctive signs such as:

• Often begins as tiny raised and crusty scabs which come off with the hair attached, leaving irritated areas of raw skin. Bacteria can develop underneath these scabs, leading to swelling and more severe infection if not properly managed.
• The condition usually starts at the pastern but may spread up the lower leg.
• It is characterised by heavy, tightly adherent scabs over raw, red, and inflamed lesions. The condition can also create cracked heels.
• The horse may show reluctance to be touched or brushed, stiffness, and possible lameness on the affected leg.
• The condition may advance to the point where swellings may also occur around other joints, especially the hocks.

In severe cases, it can lead to lameness, and the affected area can exude a cream-yellow discharge. Advanced stages are evident when there is heat and swelling in the affected limb, causing pain and discomfort to the horse.

If there is pus beneath the scabs or lesions, this may indicate a deeper infection that requires veterinary attention. When horses scratch the affected areas, it can exacerbate the damage and allow for more severe bacterial invasion.

Mud Fever Treatment

A variety of strategies must be customised according to the intensity and specific characteristics of each horse. The following mud fever remedies form part of a comprehensive approach to treatment:

1. Keep the horse in a clean, dry area: This is crucial until the condition has healed. Constant exposure to wet and muddy conditions can exacerbate the condition.
2. Regular cleaning: Remove all surface dirt and clean with warm water and an anti-bacterial soap such as Hibiscrub. If thick scabs are present, allow the lather to sit in place for several minutes before rinsing. Any loose scabs should be removed.
3. Trim feathers: Where horses have a lot of feathers and hair, an important measure involves trimming this hair from the horse’s lower leg. Having less hairy legs makes the affected area easier to clean and to dry the legs and changes the environment in which the bacteria thrive. Trimming allows air to reach the skin and facilitates the application of treatments. The organism thrives best when conditions are anaerobic and moist.
4. Use of antimicrobial ingredients: These can include Tea Tree, Oregano, Calendula, Eucalyptus, Thyme, and Rosemary. These ingredients can help to fight the bacteria causing the infection.
5. Healing support: What you can do right away is start feeding a forage-focused mineral balancer within a high-protein bucket feed. This will supply optimal levels of key minerals that the body will need to support the skin, along with the various other chemical processes within the body.
6. Medication: More stubborn cases may need additional medication between cleanings. A mixture of 0.5 to 1% topical cortisone cream, antibiotic, and antifungal can be a good approach for severely inflamed cases. Some cases may require repeat treatments to fully resolve the condition, especially if initial therapies do not lead to improvement.
7. Consult with a veterinarian if the problem is persistent: It’s important to consult with a veterinarian for a proper diagnosis and treatment plan. They may recommend specific treatments or medications based on the severity of the condition. If the condition is severe or not improving, seek further advice from your vet regarding additional guidance or treatment options.

Using pig oil and sulphur to prevent mud fever in horses

Pig oil and sulphur is a traditional remedy that has been used for generations to prevent mud fever, particularly in horses with long feathers or white legs.

This combination is especially valued in winter months or wet, muddy conditions, when the risk is highest. It offers both a physical barrier against the elements and antimicrobial protection, making it a popular and practical option for many horse owners.

Pig oil is a light mineral oil that coats the hair and skin, forming a waterproof layer that helps to repel mud and moisture. This prevents the skin from staying damp for long periods. When mixed with sulphur powder (also known as flowers of sulphur), the solution provides additional benefits. Sulphur is known for its mild antibacterial, antifungal, and antiseptic properties, helping to reduce the presence of microorganisms on the skin surface.

By creating a protective barrier and discouraging microbial growth, pig oil and sulphur help maintain healthy skin and reduce the chances of cracks or irritation that can allow infection to take hold. In feathered horses, it can also help to deter mites, which often exacerbate skin conditions by causing irritation and damage to the skin’s surface.

That said, this mixture is best used as a preventative, not a treatment. If mud fever is already present, and the skin is broken or infected, pig oil and sulphur may cause stinging or further irritation. In such cases, the infection should be resolved before using this mixture as a protective measure.

Skin sensitivity can vary between horses, so it is important to perform a patch test before applying the mixture to larger areas. Some horses may react to the sulphur or the oil, and in those cases, the mixture should be avoided or adjusted to a weaker concentration. Overuse can also lead to skin irritation or blocked pores, especially in horses with finer coats or sensitive skin.

Once it is established that a horse tolerates the mixture well, pig oil and sulphur can be used regularly during wet weather or muddy turnout to help the skin.

How to use pig oil and sulphur:

• Mix approximately 4 parts pig oil to 1 part flowers of sulphur (some owners use weaker ratios such as 5:1 or 10:1 for sensitive horses).
• Ensure the legs are clean and fully dry before application.
• Massage the mixture gently into the feathers or down to the skin, focusing on areas most at risk of mud exposure.
• Apply weekly or as needed, depending on turnout conditions and weather.
• Store the mixture in a sealed container and shake well before each use to ensure it remains evenly blended.

Pig oil and sulphur is a simple, cost-effective method of helping to protect horses. When used thoughtfully and on healthy skin, it can reduce the need for more intensive treatments later on. As with all preventative care, regular inspection of the legs and early intervention if any signs appear will provide the best results.

Less common treatments for treating mud fever

Salt therapy, or halotherapy

This is a treatment method that involves exposing horses to a fine mist or dry aerosol of salt particles, typically in a specialised room or through portable salt nebulisers. This therapy is thought to provide several health benefits for horses, particularly for respiratory and skin conditions.

Salt therapy can help in horses by leveraging salt’s natural antibacterial, antifungal, and anti-inflammatory properties.

How Salt Therapy Helps Mud Fever:

1. Antibacterial and Antifungal Action: Salt has natural antimicrobial properties, which can help kill bacteria and fungi causing the problem. Applying salt aerosols or using salt-based treatments can inhibit the growth of these harmful microorganisms on the horse’s skin, promoting healing.

2. Reduces Inflammation: The anti-inflammatory properties of salt therapy can help reduce swelling and irritation caused by mud fever. This can alleviate discomfort for the horse and help the crusty scabs heal more quickly.

3. Promotes Skin Healing: Salt therapy supports the skin’s natural healing process. It can help dry out the affected area, reducing moisture that encourages bacterial and fungal growth. Clearing out infections allows the skin to recover faster.

4. Cleanses and Soothes Wounds: Salt therapy can also help cleanse open sores and cracked heels, preventing further infection and providing soothing relief to affected horses.

Application:

• Topical Salt Solutions: You can apply saline solutions or salt-infused sprays directly to the area to promote healing and prevent infection.
• Halotherapy (Salt Aerosol): In some cases, using salt nebulisers or salt therapy rooms can benefit overall skin health, although topical treatments are usually more direct.

While salt therapy can be a helpful addition, it should be used in conjunction with other treatments, such as keeping the horse’s lower legs clean, dry, and protected.

Using Colloidal Silver

Colloidal silver is a suspension of microscopic silver particles in liquid, often marketed for its broad-spectrum antimicrobial properties. Some horse owners turn to colloidal silver as a topical treatment to help manage the infection and support healing.

Applied topically to the affected area, colloidal silver may help by reducing the microbial load on the skin, cleaning the area as a mild disinfectant and creating a more favourable environment for healing. It’s typically available in spray form or as a gel or cream, which can be gently applied to the pasterns once the area has been cleaned and dried.

However, there are some important limitations and considerations. While silver has shown antimicrobial activity in vitro, there is limited robust evidence supporting its effectiveness specifically in equine skin infections.

For more moderate or severe cases, where there is swelling, heat, pain, or spreading infection, veterinary intervention is essential. Colloidal silver should not be relied upon as a sole treatment in these situations.

What to do if the infection becomes well established?

A structured and consistent approach is essential for effective treatment. The first step is to clean thoroughly using an antibacterial shampoo such as a dilute solution of Hibiscrub or Betadine.

Gently work the solution into the area to create a rich lather, and allow it to soak for several minutes. This softens the scabs, making them easier to remove, but only remove what the horse will comfortably tolerate, without causing pain or further trauma.

After cleansing, it’s crucial to dry the area thoroughly. This can be achieved by housing the horse in a dry, clean area overnight or by using gamgee wraps and applying stable bandages to gently draw out moisture. Ensuring the skin is completely dry before applying any topical products is a key part of breaking the cycle of infection and inflammation.

Once dry, spray with prescription antibiotic spray (the vet will supply this) and apply a barrier and healing cream to protect the area from further moisture and help the skin recover.

There are many barrier creams available on the market designed to treat mud fever and create a protective layer. One of the most effective and affordable options is Sudocrem, which soothes, softens, and protects the skin from moisture and sunlight. Another option is Zinc and Castor Oil cream. In more severe cases, Sudocrem can be applied generously and the area wrapped with Gamgee and a light bandage to keep it clean and supported.

The goal of any cream is to soften the scabs, prevent skin cracking, and create a waterproof barrier against further contamination. Cracking can be extremely painful for the horse and slows down healing. Other creams that may be beneficial include tallow-based creams, Aloe Vera and Bee Propolis, Honey Heal, Aromaheel, and Cow Udder Cream. We also found the silver-based cream, Flamazine (prescription available via your vet) to be highly effective in stubborn cases.

Once the initial wash with Hibiscrub or Betadine is completed, it’s best not to wash the area again for at least a week. Over-washing can dry out the skin and interfere with healing. Instead, focus on regular application of your chosen cream on dry legs. This not only protects the skin but also gradually softens scabs, allowing them to lift off naturally over time.

Long-term healing is a balance, or a “see-saw”, between gently removing softened scabs, washing every 7 to 10 days, allowing the area to dry out completely, and reapplying creams to maintain skin integrity and protection. This cycle should be repeated until the skin is healed and free from scabs and soreness. Allowing the area to dry with exposure to the air also helps if it is carried out over a day or night.

Because mud fever is often recurrent and can be triggered by environmental factors, a permanent cure is unlikely. Management and treatment focus on ongoing control and prevention rather than complete eradication.

Of course, prevention is always better than a cure. The sooner the infection is spotted and treated, the easier it is to resolve. If caught early, it can often be managed without the need for intensive intervention. Regular checks, especially during wet or muddy weather, can help you catch the condition before it becomes established.

Prevention Techniques to Keep Your Horse Healthy

Prevention is always better than any treatment. Ensuring your horse receives all the necessary nutrients is crucial for maintaining a robust immune system and overall health.

We always strive to ensure that the basics of nutrition are covered, which include balanced minerals matched to forage (grass, hay, haylage), sufficient protein levels, and omega-3 fatty acids.

A deficiency in any of these areas will affect skin health and may affect other areas of health. The skin needs all of these basics in place, and there are always deficiencies, imbalances and antagonist mineral levels that will be playing their part in the problem.

Forage analysis tells us that the majority of UK forage is far too low in protein, often below the minimum protein requirements needed for optimal health. Minerals and the amino acids from protein are essentially the building blocks of life, so these must be a priority.

Daily leg inspections can identify early signs, ensuring prompt treatment and a greater chance of successful recovery. Stable cleanliness and environmental control are key in preventing the condition by avoiding exposure to excessively wet and muddy conditions throughout the year.

Protecting the horse’s skin from moisture and abrasions is essential, as this helps reduce susceptibility to infections. Brushing mud off with a soft-bristle brush, rather than repeated washing, is preferable.

How sunburn can be a problem in summer

Affected horses often have pink skin, which when exposed to strong sunlight without protection, can become inflamed, red, and sore. Pink noses as well as pink heels can be vulnerable. Sunburn damages the skin’s natural barrier, leaving it weakened and less able to defend against environmental stressors.

As the area begins to heal, it often becomes dry and may crack or peel, creating tiny openings in the skin. These microabrasions can easily allow pathogens like bacteria to enter the skin.

If the horse is then exposed to wet or muddy conditions, whether from standing in damp fields, frequent hosing, or walking through muddy gateways, the combination of moisture and broken skin creates the perfect environment for infection. Fungal infection and parasitic mites can also play a role, further complicating the condition.

Once the infection sets in, it triggers inflammation and irritation. The horse may develop scabs, crusting, oozing sores, and sometimes swelling of the lower limbs. In more serious cases, this can lead to significant discomfort and even lameness.

Early signs to watch for include redness or peeling on white areas of skin following sun exposure, sensitivity when the area is touched, and the appearance of small scabs on the pasterns. Left untreated, these mild symptoms can quickly progress into a more widespread and painful case of mud fever.

Preventing this cascade starts with good sun protection for vulnerable horses. Applying zinc-based creams (we love Sudocrem or Zinc and Castor ) will help prevent sunburn if applied every day. One tip here is to ensure the legs are dry before applying the cream. This prevents trapping moisture.

In sunny weather, UV-blocking socks or lightweight turnout wraps can also offer physical protection. Reducing the horse’s time in wet conditions, such as dewy pastures and using barrier creams before exposure to wet environments can protect the horse’s legs, but the legs MUST be dry before applying the barrier creams.

By understanding the link between sunburn and mud fever, horse owners can take proactive steps, in the early spring and summer, to protect their horses’ skin and avoid the cycle of inflammation and infection.

Why Some Horses Get Severe Mud Fever and Others Don’t

In any herd, it’s common to see some horses develop persistent or severe infections while others in the same conditions remain unaffected. This variation is due to several interrelated factors:

1. Skin Colour and Sensitivity

Horses with non-pigmented (pink) skin, especially under white socks or blazes, are more prone to sunburn and skin damage, which weakens the skin’s natural barrier. Once that barrier is compromised, whether from sun, chapping, or mild trauma, it’s easier for bacteria and fungi to invade. Horses with dark skin are naturally more resistant to UV damage and tend to have tougher skin, offering more protection.

2. Skin Integrity and Microtrauma

Individual horses may have subtle conformational or movement-related factors that lead to repeated microtrauma on the pasterns, such as brushing, overreaching, or fetlock flexion in deep mud. This constant irritation and the raw skin underneath weaken the skin and make it more vulnerable to infection.

3. Immune System Differences

Some horses have a stronger local immune response in the skin, allowing them to fight off microbial invaders more effectively. Others, especially those under stress, with metabolic issues, chronic pain, or compromised nutrition, may have a weakened immune response, allowing infections like mud fever to take hold more easily and progress more severely.

4. Feathering and Hair Type

Horses with thick feathers (e.g., cobs, draft types) and matted hair can trap moisture and mud close to the skin. While thick feathers can offer protection, if not maintained, they can also create a perfect environment for bacteria and leg mites. Horses with finer coats often dry faster and accumulate less mud.

5. Presence of Parasites (Mites)

In feathered horses, especially, chorioptic mites are common and can mimic or worsen mud fever. Some horses may carry mites without symptoms, while others have intense irritation and secondary infection. A mite infestation can make an infection more severe and harder to resolve.

6. Nutritional Status

Poor hoof and skin quality are often linked to deficiencies in key nutrients like zinc, copper, vitamin E, and essential fatty acids, especially in winter months when forage quality and protein is low. Horses with unbalanced diets may have weaker skin and slower healing, making them more susceptible and slower to recover.

7. Grooming, Management, and Hygiene

Even in the same field, individual care routines differ. Horses that are regularly checked, cleaned, and dried are more likely to have mild or no symptoms. Others may have damp, dirty legs for long periods, which encourages infection. Washing the horse’s legs daily or using harsh products can also strip the skin’s protective oils and worsen the problem.

In Summary

Mud fever isn’t just about mud; it’s about how resilient the individual horse’s skin is, how effectively their body fights infection, and how they are managed day-to-day.

One horse may have thick, dark, pigmented, healthy skin, a strong immune system, and fast-drying legs, while another might have pink, fragile skin, poor nutrition, and stand in wet conditions longer. The combination of these factors explains why some horses never get the problem, while others struggle every winter and summer.

Proper grooming

Proper grooming plays a significant role in prevention. Clipping horses’ hairy legs can make it easier to keep the legs clean and dry and stop matted hair.

Post-washing, it’s imperative to thoroughly dry the horse’s legs to avoid the moist conditions that could trigger mud fever. Ensuring thorough drying after washing and regular brushing of the horse’s legs daily can be a game-changer for prevention.

Environmental management

Managing the surroundings is a decisive element in averting mud fever. Hard-standing areas around high-traffic zones help to avoid muddy and wet conditions. Furthermore, maintaining clean bedding is crucial to prevent skin damage and reduce susceptibility to the problem in muddy conditions.

Frequently Asked Questions

What is mud fever also known as?

The medical name is Equine Pastern Dermatitis. Common names include greasy heel, scratches, mud rash, dew poisoning, cracked heel, and grapes, depending upon where you live in the world.

What are the signs of mud fever?

The signs of mud fever include crusty scabs, hair loss, redness, and discharge, and in severe cases, it can lead to lameness and pain. Be vigilant for these symptoms to take prompt action if needed.

How is mud fever diagnosed?

It is diagnosed through physical examination and clinical signs assessment. In some cases, a veterinarian may conduct a swab test to check for bacterial growth and sensitivity.

What are the options for treating mud fever?

It’s important to address the underlying cause, manage the environment, cleanse the skin, and consider using specific medications like topical treatments and systemic antibiotics. Anti-inflammatories may also be prescribed.

How can mud fever be prevented?

Ensure your horse has the nutritional basics covered. This would be balanced minerals matched to forage (grass, hay, haylage), sufficient protein levels, and omega 3. This creates more robust and resilient skin structure plus accelerated healing time. Broad-spectrum balancers will not cover the imbalances when horses are eating a forage-focused diet. Feed a specific forage focused balancer to ensure the correct levels of nutrients are balanaced each day.

Minimise exposure to moisture and mud, clip excessive hair, avoid frequent washing, use waterproofing agents, ensure a fully balanced diet to support immune health, avoid allergenic bedding, block UV light, spot the signs early and maintain good hygiene.

Summary

In conclusion, while common in horses, this problem can be managed effectively with the right knowledge and care. Understanding its causes, recognising its symptoms, and knowing how to treat and prevent it are crucial steps in maintaining your horse’s health.

Remember, your horse’s health is in your hands. By taking proactive steps in managing and preventing mud fever, you can ensure your horse leads a healthy, comfortable life.