Spot it early. Treat it right. Keep it from coming back.

If you've ever noticed crusty, irritated skin at the back of your horse's pasterns, you've likely encountered pastern dermatitis, more commonly called scratches. It goes by many names: mud fever, greasy heel, cracked heels, dew poisoning. Whatever you call it in your barn, the message is the same: it's uncomfortable for your horse, stubbornly persistent, and a lot easier to prevent than it is to treat once it takes hold.

Here's what you need to know about why it happens, how to recognize it, and what to do about it.

What Is Pastern Dermatitis?

Pastern dermatitis isn't a single disease; it's a skin syndrome, and there's rarely just one cause. The condition affects the skin of the pastern and heel, a region that sits right at the base of the horse's leg and takes a beating every single day. It flexes constantly, collects moisture and mud, and in horses with heavy feathering, it can trap debris against the skin for hours at a time.

The result is inflammation that can range from mild redness and scale to painful, weeping sores, cracked skin, and significant lameness if left untreated.

Pastern dermatitis is considered a multifactorial condition, meaning multiple causes — environmental, microbial, and physiological — typically contribute simultaneously.

Why Does It Happen? Understanding the Causes

The most important step in treating scratches is getting to the bottom of what's actually driving it in your horse. Here are the most common contributors:

Wet, muddy conditions are the classic trigger. Prolonged moisture softens and breaks down the skin barrier, making it vulnerable to infection. Horses kept in wet paddocks, poorly drained pastures, or on muddy ground are at significantly higher risk. Paradoxically, frequent leg washing, particularly without thorough drying afterward, can make things worse.

Bacterial infection is one of the most frequent drivers once the skin barrier is compromised. Staphylococcus spp. and Streptococcus spp. are commonly isolated from affected tissue. Dermatophilus congolensis, the same organism that causes rain rot, can also infect the lower limbs.

Fungal organisms can also play a role, particularly in chronic or recurrent cases that don't respond well to antibacterial treatment alone.

Chorioptic mange — caused by the mite Chorioptes equi — is a significant and frequently missed cause, especially in draft breeds with feathering. Mites cause intense itching, and the horse's stomping and self-trauma perpetuate the skin damage. If mites are at the root of the problem, treating the secondary skin infection without addressing the mites will get you nowhere. Your veterinarian can diagnose mite infestations through skin scrapings.

Heavy feathering doesn't cause scratches on its own, but it creates the perfect conditions for it. Clydesdales, Shires, Friesians, and similar breeds trap moisture and debris under all that leg hair. Many owners of feathered breeds clip the pasterns during wetter months as a preventive measure.

White or unpigmented skin on the lower leg is more susceptible to photosensitization, a reaction to ultraviolet light that can cause sunburn-like lesions on exposed, lightly pigmented skin. Photosensitization can look a lot like scratches and sometimes occurs alongside it.

Underlying systemic conditions should be considered in horses with chronic, recurring, or treatment-resistant scratches. Equine pastern vasculitis, pemphigus foliaceus, and chronic progressive lymphedema (common in draft breeds) can all present as persistent lower-leg skin disease and require veterinary diagnosis and management.

How to Recognize It

Scratches often starts quietly. Early signs include:

●     Redness or swelling in the hollow of the heel or along the back of the pastern

●     Flaky, scaling skin

●     Small scabs forming over moist, weeping areas

●     Matted or crusted hair

As it progresses, the scabs thicken and multiply, the skin underneath becomes raw and painful, and the pastern may develop deep cracks. In more advanced cases, the lower leg can swell significantly. Lameness may follow when pain and restricted movement become severe.

In horses with feathering, early signs are easy to miss entirely until the condition is well established — which is one more reason to make regular hands-on leg checks part of your grooming routine, especially in wet weather.

When to Call the Vet

Some cases of pastern dermatitis need professional attention. Reach out to your veterinarian if:

●     The horse is lame

●     The leg is significantly swollen

●     The condition doesn't improve with two weeks of consistent treatment

●     Lesions are present on multiple limbs

●     The horse has a history of chronic or recurring scratches

●     You suspect mites, photosensitization, or an underlying systemic condition

Your vet may recommend skin scrapings to check for mites, bacterial culture to identify the specific organisms involved, or a biopsy if an immune-mediated or other underlying cause is suspected.

Treatment: What to Do

Mild to moderate cases can often be managed at home, but don't underestimate this condition. It’s time to call your veterinarian if the condition doesn’t improve with appropriate care within a week or two.

Step 1: Clip the area. Carefully trim the hair around the affected pastern so you can see what you're working with and so treatments can reach the skin. Trimming can be important for feathered breeds.

Step 2: Clean — but don't over-scrub. Gently wash the area with a medicated shampoo, like Silver Honey® Rapid Skin Relief Medicated Shampoo, to help reduce bacteria and soften the scabs. Avoid scrubbing aggressively.

Step 3: Dry completely. This step is non-negotiable. Applying any product to wet skin or returning your horse to a muddy environment before the area is fully dry will undermine your efforts. Patting with a clean towel, followed by drying with a hair dryer, works well.

Step 4: Apply treatment. Silver Honey® Rapid Skin Relief Vet Strength Scratches Spray was developed specifically for pastern dermatitis. It harnesses the natural power of Manuka Honey and MicroSilver BG®, along with an essential oil blend of oregano, tea tree, and lavender. The formula's RapidSorb™ Technology microencapsulates the key ingredients so they penetrate through thickened skin and scabs to get where they need to go. It's proven to stop 99.9% of bacteria immediately and provides long-lasting antibacterial and antifungal activity, without the need for harsh chemicals or antibiotics.

A note on scabs: The instinct to remove them can be strong, but try to resist. Forcibly pulling scabs off is painful for the horse and can cause additional trauma to the tissue underneath. Allow consistent treatment and natural debridement to do the work. The scabs should soften and begin to release on their own over time.

Step 5: Get the horse out of the mud. Treatment won't get far if the contributing environment doesn't change. Dry footing, clean bedding, and reduced standing time in wet areas are essential parts of recovery.

Prevention: Your Best Defense

Once you've dealt with a case of scratches, you'll want to do everything in your power to keep it from coming back. The good news is that prevention is largely about management.

●     Keep legs clean and dry. After rides in wet or muddy conditions, rinse off mud and dry the pasterns thoroughly before turning out or stabling.

●     Improve your footing. Address drainage issues in paddocks and sacrifice areas. Adding gravel or sand to high-traffic areas around water troughs and gates can make a big difference.

●     Check legs regularly. The earlier you catch a problem, the easier it is to manage. Make a habit of running your hands down your horse's pasterns during grooming.

●     Consider clipping feathered legs during wetter seasons if your horse is prone to recurring issues.

●     Watch horses with white legs for any early skin changes, especially in spring and summer.

A Final Word

Scratches is one of those conditions that can feel deceptively minor at first, until it isn't. Catching it early, understanding what's driving it in your horse, and treating it consistently with products designed for the job gives you the best shot at a quick recovery. Good management practices go a long way toward keeping it from recurring.

References

●      Merck Veterinary Manual. (2022). Pastern Dermatitis in Horses. Merck & Co.

●      Mecklenburg, L., Linek, M., & Tobin, D.J. (2009). Hair Loss Disorders in Domestic Animals. Wiley-Blackwell.

●      Scott, D.W., & Miller, W.H. (2011). Equine Dermatology (2nd ed.). Saunders/Elsevier.

●      Pilsworth, R.C., & Knottenbelt, D. (2007). Pastern dermatitis. Equine Veterinary Education, 19(5), 270–277. https://doi.org/10.2746/095777307X186694

●      White, S.D. (2005). Pastern dermatitis. Clinical Techniques in Equine Practice, 4(1), 4–10. https://doi.org/10.1053/j.ctep.2005.04.004