Pastern Dermatitis in Horses: Causes, Treatment and Prevention

By Dr Duncan Houston

Pastern dermatitis is one of those horse skin problems that sounds simple until you try to fix it.

It is often called scratches, mud fever, greasy heel, mud rash, cracked heels, or dew poisoning. The names vary, but the pattern is usually the same: sore, inflamed, crusted skin around the pastern, often on the back of the lower leg. In mild cases, it may look like a few small scabs. In more serious cases, it can become swollen, painful, infected, itchy, oozing, and severe enough to cause lameness.

The most important thing to understand is that pastern dermatitis is not one single disease. It is a reaction pattern. Moisture, mud, bacteria, fungi, mites, allergies, insects, sunlight sensitivity, poor skin barrier function, and heavy feathering can all play a role. UC Davis describes pastern dermatitis as a disease complex that can be triggered by different causes, which is why guessing the cause often leads to frustrating treatment failures. (Centre for Equine Health)

Quick Answer

Pastern dermatitis in horses is inflammation of the skin around the pastern, most often seen as scabs, crusts, redness, swelling, oozing, sensitivity, itching, or lameness. It is commonly worsened by wet conditions, mud, bacteria, fungi, mites, allergies, insect irritation, sunlight sensitivity, and heavy lower-leg feathering. Mild cases may improve with clipping, gentle cleaning, drying, and vet-directed topical care, but painful, spreading, swollen, infected, recurrent, or lame cases need veterinary assessment.

What Is Pastern Dermatitis?

Pastern dermatitis is inflammation affecting the skin around the pastern. It most commonly affects the back of the pastern, but it can extend to the heel bulbs, fetlock, and sometimes up toward the cannon bone.

You may hear it called:

• Scratches

• Mud fever

• Greasy heel

• Mud rash

• Cracked heels

• Dew poisoning

• Pastern folliculitis

Those names are useful in conversation, but clinically they can be misleading. They make it sound like the condition is always caused by mud, when that is not true.

In practice, pastern dermatitis usually develops when the skin barrier is damaged. Once the skin is weakened, bacteria, fungi, mites, moisture, friction, sunlight, or irritants can trigger inflammation and infection. MSD Veterinary Manual notes that dermatitis is a broad term for skin inflammation and that resolving it requires identifying the underlying cause and treating secondary infections or complications. (MSD Veterinary Manual)

That is the real key. You are not just treating scabs. You are trying to work out why the skin became inflamed in the first place.

What Does Pastern Dermatitis Look Like?

Signs vary depending on the cause and severity.

Common signs include:

• Small scabs at the back of the pastern

• Red, inflamed skin under the hair

• Crusty or greasy patches

• Oozing or discharge beneath scabs

• Hair loss

• Thickened skin

• Swelling around the pastern or lower limb

• Pain when the area is touched

• Itching, rubbing, stamping, or chewing

• Sensitivity during grooming

• Lameness in more severe cases

UC Davis notes that pastern dermatitis can begin with redness, oozing, crusting, erosions, and ulcerations, followed by swelling. The skin may be itchy and sensitive, and lameness can occur in some cases. (Centre for Equine Health)

A mild case may look like a few dry scabs. A severe case may look like a wet, swollen, painful lower leg with thick crusts and discharge. The second horse needs much more than a quick wash and a hopeful dab of cream.

Why Do Horses Get Pastern Dermatitis?

Pastern dermatitis usually develops when several factors overlap.

Common contributors include:

Moisture and Mud

Wet bedding, muddy paddocks, repeated washing, wet grass, and legs that stay damp for long periods can weaken the skin barrier. Purdue University notes that excessively moist or dirty environments, repeated wetting and drying, damp pastures, and wet stalls create conditions where bacteria and fungi can enter breaks in the skin. (Purdue Vet School)

This is why pastern dermatitis often flares during wet seasons or in horses standing around gateways, troughs, muddy yards, or damp bedding.

Bacterial Infection

Bacteria commonly complicate pastern dermatitis. Sometimes they are the main cause. Sometimes they move in after moisture, mites, trauma, allergy, or irritation has already damaged the skin.

A bacterial component is more likely when the skin is:

• Wet

• Oozing

• Smelly

• Hot

• Painful

• Swollen

• Producing yellow or white discharge

Fungal Infection

Fungal or dermatophyte involvement can look similar to bacterial dermatitis. It may cause crusting, hair loss, scaling, and spread between horses or through contaminated equipment.

This matters because antibiotics will not fix a fungal problem.

Mites

Chorioptes mites can cause irritation around the lower legs, especially in heavily feathered breeds. Horses may stamp, chew, rub, or become very sensitive when the lower legs are handled.

Mite-related pastern dermatitis is often missed because the mites are not visible to the naked eye and may hide under feathers and crusts.

Heavy Feathering

Draft horses and horses with long lower-leg hair are at higher risk because feathering traps moisture, mud, debris, mites, and skin flakes. UC Davis notes that pastern dermatitis is most common in draft breeds and horses with heavy feathering on the lower legs, and Purdue also highlights draft horses with feathers or long fetlock hair as a higher-risk group. (Centre for Equine Health)

This does not mean feathers are bad. It means the skin underneath them needs regular checking.

White or Unpigmented Skin

Horses with white legs may be more prone to pastern dermatitis because unpigmented skin is more vulnerable to sun damage, chafing, and abrasions. UC Davis and Purdue both note increased susceptibility in horses with white or unpigmented lower-leg skin. (Centre for Equine Health)

Allergies and Insect Irritation

Insects, especially biting flies, midges, and mosquitoes, can irritate the skin and trigger rubbing, inflammation, and secondary infection.

Allergic horses may have signs elsewhere too, such as belly irritation, mane and tail rubbing, hives, or seasonal itching.

Irritants and Trauma

Plant material, abrasive bedding, poorly fitted boots, wraps, over-washing, harsh chemicals, and repeated friction can all damage the pastern skin.

Once small cracks appear, infection can follow.

Severity Guide: How Worried Should You Be?

Severity	What it looks like	What to do
Mild	A few small dry scabs, little or no swelling, horse comfortable, no lameness	Keep the area clean and dry, inspect daily, and arrange vet advice if it does not improve within a few days
Moderate	More scabs, redness, mild oozing, sensitivity, itching, or repeated flare-ups	Book a vet check. The cause may be bacterial, fungal, parasitic, allergic, or environmental
Severe	Swelling, heat, pain, thick crusts, discharge, bleeding, spreading lesions, or lameness	Call your vet promptly. Infection, mites, deep inflammation, or cellulitis may be involved
Critical	Marked lameness, severe swelling, fever, deep wounds, white or yellow discharge, depression, or rapid worsening	Treat as urgent. Do not continue home treatment while the leg deteriorates

The decision point is simple: if the horse is lame, swollen, painful, oozing, or worsening, this is no longer a minor skin problem.

What Else Can Look Like Pastern Dermatitis?

Because pastern dermatitis is a reaction pattern, not one diagnosis, several conditions can look similar.

Important rule-outs include:

Chorioptic Mange

Mites are especially important in heavily feathered horses. Look for stamping, chewing, rubbing, and recurring scabs under feathers.

Dermatophytosis or Ringworm

Ringworm can cause hair loss, scaling, crusting, and spread between horses or people. It needs a different treatment plan from bacterial scratches.

Photosensitivity

White legs can become inflamed when sunlight triggers skin damage. This can be primary or secondary to liver disease or plant exposure.

Contact Irritation

Topical products, harsh disinfectants, bedding, mud, boots, wraps, or over-washing can irritate the skin.

Chronic Progressive Lymphedema

This is especially relevant in some draft breeds. It can cause chronic lower-leg swelling, thickened skin, folds, nodules, and repeated skin infections. It may be mistaken for recurring mud fever.

Cellulitis or Lymphangitis

If bacteria enter deeper tissues, the limb may become hot, swollen, painful, and the horse may become lame or unwell. This is much more serious than surface scabbing.

Wounds or Pastern Lacerations

A cut, puncture, wire injury, heel bulb wound, or hidden trauma can be mistaken for dermatitis, especially once scabs form.

The mistake I see most often is treating every pastern scab as “mud fever.” Sometimes it is. Sometimes it is mites, fungal disease, photosensitivity, chronic lower-leg disease, or infection hiding behind the same crusty appearance.

When Is Pastern Dermatitis an Emergency?

Pastern dermatitis is not always an emergency, but some cases need urgent veterinary care.

Call your vet promptly if your horse has:

• Lameness

• Marked swelling

• Heat in the lower limb

• Severe pain when touched

• Rapidly spreading lesions

• Deep cracks or ulceration

• Bleeding skin

• Yellow or white discharge

• A foul smell

• Fever

• Loss of appetite

• Depression or dullness

• A wound or puncture near the pastern

• Severe itching, stamping, or self-trauma

• More than one limb severely affected

• No improvement despite treatment

Purdue advises veterinary attention when scratches are not responding to treatment, or when there is severe lameness, deep wounds, swelling, excessive heat, or white/yellow discharge. (Purdue Vet School)

If the leg is hot, swollen, and lame, do not keep washing and applying cream for another week. That horse may need systemic treatment, pain relief, further diagnostics, or deeper infection management.

How Vets Diagnose Pastern Dermatitis

A vet will usually start by looking at the pattern.

Important questions include:

• Which legs are affected?

• Is it one leg, both hind legs, or all four?

• Is the horse itchy or painful?

• Is there lameness?

• Are there mites, fungi, bacteria, or moisture triggers?

• Is the horse heavily feathered?

• Are the legs white or unpigmented?

• Is this seasonal?

• Has it happened before?

• What products have already been used?

• Is the horse in wet bedding or muddy turnout?

• Are other horses affected?

Depending on the case, diagnostics may include:

• Skin scrapings for mites

• Tape preparations

• Hair plucks

• Cytology to look for bacteria or yeast

• Bacterial culture

• Fungal culture

• Biopsy in chronic or unusual cases

• Radiographs if lameness or deeper disease is suspected

UC Davis notes that diagnosis may involve biopsy, bacterial and fungal cultures, skin scrapings to rule out parasites such as Chorioptes mites, and radiographs when other causes of lameness need to be ruled out. (Centre for Equine Health)

This is why “just put something on it” is not always enough. If the underlying cause is wrong, the treatment will be wrong.

What Should You Do First?

If you notice scabs or soreness around your horse’s pastern, take a calm, structured approach.

1. Inspect the Area Properly

Part the hair and look at the skin, not just the outside of the coat.

Check for:

• Redness

• Scabs

• Crusts

• Oozing

• Swelling

• Heat

• Pain

• Hair loss

• Cracks

• Discharge

• Lameness

Take photos. They are useful for tracking progression and showing your vet whether the condition is improving or spreading.

2. Keep the Area Dry

Dryness is one of the most important foundations of recovery.

Move the horse away from constant mud if possible. Use clean, dry bedding. Avoid repeated wetting and drying. After washing, dry the area carefully with a clean towel.

UC Davis recommends avoiding recurrent moisture exposure, drying pastern areas well after bathing, keeping lower-leg hair clipped when appropriate, and maintaining clean, dry bedding. (Centre for Equine Health)

3. Clip Long Hair if Needed

Clipping helps you see the skin and allows treatment to reach the affected area.

This is especially important if the horse has:

• Heavy feathers

• Matted hair

• Moist scabs hidden under hair

• Recurrent pastern dermatitis

• Suspected mites

• Oozing or infection

Purdue recommends carefully clipping hair away from the infected area while avoiding scraping or breaking the skin. (Purdue Vet School)

4. Clean Gently

Gentle cleaning may help, but rough scrubbing can make pastern dermatitis worse.

Your vet may recommend an antibacterial shampoo such as chlorhexidine, povidone-iodine, or benzoyl peroxide, or an antifungal shampoo such as miconazole, depending on the suspected cause. Purdue advises gentle washing, allowing shampoo contact time, rinsing carefully, avoiding harsh chemicals, and not pulling or picking scabs. (Purdue Vet School)

The goal is to soften debris and reduce contamination, not sandblast the leg into submission.

5. Do Not Rip Off Scabs

Scabs can be painful and may cover raw tissue.

If scabs need to be removed, they should be softened first and removed gently. Some horses require sedation or pain relief for proper cleaning. Forcing dry scabs off can cause bleeding, pain, and more inflammation.

6. Apply Medication Only as Directed

Topical treatment depends on the cause.

A vet may recommend:

• Antibacterial ointment

• Antifungal treatment

• Anti-inflammatory medication

• Topical steroid combinations in selected cases

• Barrier creams

• Mite treatment

• Systemic antibiotics if infection is deeper or severe

Purdue notes that veterinary-recommended ointments may include antibiotics, antifungals, steroids, and other medications, and that systemic antibiotics may be needed in more serious cases. (Purdue Vet School)

Avoid layering multiple products together unless your vet advises it. Five creams at once rarely make the plan five times better.

Should You Wrap Pastern Dermatitis?

Sometimes yes, sometimes no.

Wrapping may help keep a treated area clean in selected cases, but wraps and boots can also trap moisture, heat, and debris. That can make pastern dermatitis worse if they are used incorrectly or left on too long.

Do not wrap unless your vet has advised it, especially if the skin is wet, oozing, infected, swollen, or painful.

Purdue specifically advises not using wraps or boots that retain moisture around infected areas and not sharing boots between horses. UC Davis also warns against long-term use of boots and wraps that can trap moisture. (Purdue Vet School)

Common Treatment Approaches

Treatment should be based on the cause, but common elements include:

Clipping and Skin Access

This allows cleaning, diagnosis, monitoring, and medication contact.

Gentle Cleansing

A vet-directed antibacterial or antifungal wash may be used. Frequency depends on severity and response. Over-washing can dry and irritate the skin, so more is not always better.

Drying

The area should be dried thoroughly after washing. Leaving the skin damp under hair, feathers, boots, or wraps can perpetuate the problem.

Topical Medication

This may include antibacterial, antifungal, anti-inflammatory, or barrier products depending on the diagnosis.

Mite Control

If mites are involved, topical or systemic mite treatment may be needed under veterinary guidance. In-contact horses and grooming equipment may also need attention.

Systemic Medication

Oral or injectable antibiotics, anti-inflammatories, pain relief, or other medication may be needed if the condition is severe, infected, painful, or spreading.

Environmental Change

If the horse stays in mud, wet bedding, or damp conditions, treatment is likely to struggle. Environment is not a side issue. It is part of the treatment.

Common Mistakes Owners Make

Treating Every Case the Same Way

Pastern dermatitis has many causes. A treatment that works for one horse may fail completely in another.

Waiting Too Long

Small scabs are easier to manage than swollen, infected, painful lower legs. Early treatment is usually simpler and cheaper.

Picking Scabs Aggressively

This causes pain and trauma. Soften first, remove gently if appropriate, and involve your vet if the horse is painful.

Over-Washing

Constant washing can keep the skin wet and irritated. Cleaning matters, but drying matters just as much.

Using Harsh Products

Bleach, strong disinfectants, caustic scab removers, essential oils, and random stable-yard mixtures can damage already inflamed skin.

Wrapping Wet Skin

Boots and wraps can trap moisture and worsen dermatitis if used incorrectly.

Ignoring Mites in Feathered Horses

If a feathered horse keeps stamping, chewing, and recurring, mites need to be considered.

Treating Infection but Missing the Cause

Antibiotics may calm secondary infection, but if mud, mites, moisture, sunlight, or chronic lower-leg disease remain, the problem often returns.

How To Prevent Pastern Dermatitis

Prevention is about protecting the skin barrier.

Useful prevention steps include:

• Check pasterns regularly during grooming

• Keep legs as dry as practical

• Avoid prolonged turnout in deep mud

• Fill muddy areas around gates and water troughs

• Use clean, dry bedding

• Dry legs thoroughly after washing or wet turnout

• Avoid repeated wetting and drying when possible

• Clip heavy feathers in horses with recurrent problems if advised

• Do not leave boots or wraps on damp legs

• Do not share boots, wraps, towels, or grooming tools between affected horses

• Manage insects with sensible fly control

• Use sun protection strategies for white legs when needed

• Treat small areas early before swelling or infection develops

• Investigate recurring cases rather than repeating the same failed treatment

Purdue recommends dry footing, dry bedding, avoiding heavy dew or frost turnout when relevant, not sharing boots, considering clipping in horses with long leg hair or feathers, and frequent leg checks for early signs. (Purdue Vet School)

The best prevention is boring, consistent management. Unfortunately, boring management is often what saves you from exciting vet bills.

Will My Horse Recover?

Many horses recover well when the cause is identified early and treatment is consistent.

The prognosis is best when:

• The case is caught early

• The underlying cause is identified

• The skin is kept dry

• Secondary infection is controlled

• The horse is not left standing in mud

• Mites, fungi, or allergies are not missed

• The owner avoids harsh scrubbing and random products

• Recurring cases are investigated properly

UC Davis notes that early, accurate diagnosis and appropriate treatment result in the most successful outcomes and help prevent severe chronic changes. Secondary bacterial infections are common and can complicate diagnosis, treatment, and recovery. (Centre for Equine Health)

If the horse has chronic lower-leg disease, heavy feathering, repeated wet exposure, or long-standing thickened skin, the goal may be long-term control rather than a one-time cure.

FAQs

Can pastern dermatitis go away on its own?

Very mild cases may improve if the trigger is removed and the area is kept clean and dry. However, if there is swelling, pain, oozing, lameness, itching, or repeated recurrence, it should not be left to resolve on its own.

Is pastern dermatitis painful?

Yes, it can be. Mild cases may only be mildly irritating, but severe pastern dermatitis can be very painful, especially when scabs, swelling, infection, cracks, or lameness are present.

Should I remove the scabs?

Do not pull off dry scabs. They should be softened first and removed gently only when appropriate. If your horse is painful, sedation or veterinary treatment may be needed.

What is the best treatment for scratches in horses?

There is no single best treatment for every case. The right treatment depends on whether the cause is bacterial, fungal, mite-related, allergic, moisture-related, sun-related, or part of a chronic lower-leg disease. A good plan usually includes skin access, gentle cleaning, drying, targeted medication, and environmental control.

When should I call a vet?

Call a vet if the area is swollen, hot, painful, oozing, spreading, recurrent, or causing lameness. Also call if the horse has fever, discharge, deep cracks, severe itching, or no improvement after initial care.

Final Thoughts

Pastern dermatitis is common, but it should not be treated casually.

The scabs are only the visible part of the problem. Underneath, there may be moisture damage, bacterial infection, fungal disease, mites, allergy, sunlight sensitivity, chronic lower-leg disease, or a combination of several factors.

The best approach is to identify the cause, protect the skin barrier, keep the area dry, clean gently, use targeted treatment, and act early if the leg becomes painful, swollen, infected, or lame.

A few small scabs may be manageable. A hot, swollen, painful lower leg is a different situation entirely. Knowing that difference is what protects your horse’s comfort, soundness, and recovery.

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If you are unsure whether your horse’s pastern dermatitis is mild, infected, mite-related, or urgent, ASK A VET™ can help you work through the signs and decide what to do next.